Provider crashes with nil pointer errors when reading VMs with incomplete configurations

[anton-ane]

Summary

The Terraform Proxmox provider (v3.0.2-rc05) crashes with panic errors (interface conversion: interface {} is nil, not string) when attempting to read VMs that have incomplete or partially configured components. This can occur with IDE disk devices, CPU configurations, or other VM attributes that are in an incomplete state (e.g., added via terraform with "automatic_reboot = false" argument, or added via Proxmox Web UI without VM reboot).

Provider Version

terraform-provider-proxmox v3.0.2-rc05

Terraform Version

Terraform v1.13.4

Affected Resource(s)

• proxmox_vm_qemu

Terraform Configuration

resource "proxmox_vm_qemu" "ftp3" {
  name         = "ftp3"
  target_nodes = ["proxmox4"]
  clone        = "alma-clean-linux-template"
  full_clone   = true

  define_connection_info = true
  onboot                 = true
  agent                  = 1
  qemu_os                = "l26"
  automatic_reboot       = false
  automatic_reboot_severity = "warning"
  scsihw                 = "virtio-scsi-single"
  tags                   = "terraform"

  memory  = 4096
  balloon = 0

  cpu {
    cores   = 2
    sockets = 2
    type    = "x86-64-v2-AES"
    numa    = false
  }

  disk {
    slot    = "scsi0"
    type    = "disk"
    storage = "HA-pool"
    size    = "50G"
  }

  network {
    id     = 0
    model  = "virtio"
    bridge = "vmbr0"
  }

  ipconfig0 = "ip=dhcp"
}

Steps to Reproduce

Example: Incomplete IDE Disk Device

1. Create a VM using Terraform with terraform plan and terraform apply - succeeds
2. Add a DVD/CD-ROM image to the VM via Proxmox Web UI:
   • Go to VM Hardware settings
   • Add DVD/CD-ROM device at Bus/Device IDE/2
   • Select an ISO image
   • Important: Do NOT reboot the VM (device shows as yellow - not fully implemented)
3. Run terraform plan -target proxmox_vm_qemu.ftp3 again
4. Provider crashes with panic error in disksIde() function

Note: Similar errors can occur in other scenarios when VM configurations are incomplete:

• CPU configuration parsing - crashes in GetCPU()
• Other VM attributes in incomplete states - crashes in mapToStruct()

Expected Behavior

Terraform should be able to read the VM state even when VM components are in an incomplete or partially configured state. The provider should handle nil values and incomplete configurations gracefully.

Actual Behavior

The provider crashes with a panic error when trying to parse VM configurations that contain nil values:

panic: interface conversion: interface {} is nil, not string

The crash occurs in various functions depending on which component has nil values:

• disksIde() when IDE disk devices are incomplete
• GetCPU() when CPU configuration is incomplete
• mapToStruct() when other VM attributes are incomplete

Error Output

proxmox_vm_qemu.ftp3: Refreshing state... [id=proxmox5/qemu/145]

Planning failed. Terraform encountered an error while generating this plan.

╷
│ Error: Request cancelled
│ 
│   with proxmox_vm_qemu.ftp3,
│   on ftp3.tf line 1, in resource "proxmox_vm_qemu" "ftp3":
│    1: resource "proxmox_vm_qemu" "ftp3" {
│ 
│ The plugin.(*GRPCProvider).ReadResource request was cancelled.
╵

Stack trace from the terraform-provider-proxmox_v3.0.2-rc05 plugin:

panic: interface conversion: interface {} is nil, not string

goroutine 24 [running]:
github.com/Telmate/proxmox-api-go/proxmox.(*rawConfigQemu).disksIde(0xc000f839d8, 0xc000efe184)
	github.com/Telmate/proxmox-api-go@v0.0.0-20251016192144-4a331a14ad5c/proxmox/config__qemu__disk__ide.go:108 +0x28e
github.com/Telmate/proxmox-api-go/proxmox.(*rawConfigQemu).GetDisks(0xc000f839d8)
	github.com/Telmate/proxmox-api-go@v0.0.0-20251016192144-4a331a14ad5c/proxmox/config__qemu__disk.go:1075 +0x4a
github.com/Telmate/proxmox-api-go/proxmox.(*rawConfigQemu).get(0xc000f839d8, 0xc000bc0d20)
	github.com/Telmate/proxmox-api-go@v0.0.0-20251016192144-4a331a14ad5c/proxmox/config__qemu.go:1148 +0x445
github.com/Telmate/proxmox-api-go/proxmox.(*rawConfigQemu).Get(0xc00028d710?, 0xf26a49?)
	github.com/Telmate/proxmox-api-go@v0.0.0-20251016192144-4a331a14ad5c/proxmox/config__qemu.go:1123 +0x13
github.com/Telmate/terraform-provider-proxmox/v2/proxmox.resourceVmQemuRead({0x108b6d8, 0xc0000faee0}, 0xc00028d710, {0xd6dea0?, 0xc000a2d2c0})
	github.com/Telmate/terraform-provider-proxmox/v2/proxmox/resource_vm_qemu.go:997 +0x77c
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*Resource).read(0xc000540a00, {0x108b630, 0xc000dcd6e0}, 0xc00028d710, {0xd6dea0, 0xc000a2d2c0})
	github.com/hashicorp/terraform-plugin-sdk/v2@v2.37.0/helper/schema/resource.go:866 +0x119
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*Resource).RefreshWithoutUpgrade(0xc000540a00, {0x108b630, 0xc000dcd6e0}, 0xc000e36270, {0xd6dea0, 0xc000a2d2c0})
	github.com/hashicorp/terraform-plugin-sdk/v2@v2.37.0/helper/schema/resource.go:1162 +0x52a
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*GRPCProviderServer).ReadResource(0xc00037c000, {0x108b630?, 0xc000dcd620?}, 0xc0005de7d0)
	github.com/hashicorp/terraform-plugin-sdk/v2@v2.37.0/helper/schema/grpc_provider.go:908 +0xb6d
github.com/hashicorp/terraform-plugin-go/tfprotov5/tf5server.(*server).ReadResource(0xc0002800a0, {0x108b630?, 0xc000ccae0?}, 0xc0000fa9a0)
	github.com/hashicorp/terraform-plugin-go@v0.28.0/tfprotov5/tf5server/server.go:859 +0x2f3
github.com/hashicorp/terraform-plugin-go/tfprotov5/internal/tfplugin5._Provider_ReadResource_Handler({0xefdb20, 0xc0002800a0}, {0x108b630, 0xc000ccae0}, 0xc0001a5c80, 0x0)
	github.com/hashicorp/terraform-plugin-go@v0.28.0/tfprotov5/internal/tfplugin5/tfplugin5_grpc.pb.go:651 +0x1a9
google.golang.org/grpc.(*Server).processUnaryRPC(0xc000262400, {0x108b630, 0xc000dcca50}, 0xc00028aba0, 0xc000982630, 0x1729fb8, 0x0)
	google.golang.org/grpc@v1.72.1/server.go:1405 +0x1036
google.golang.org/grpc.(*Server).handleStream(0xc000262400, {0x108c010, 0xc0007a01a0}, 0xc00028aba0)
	google.golang.org/grpc@v1.72.1/server.go:1815 +0xb88
google.golang.org/grpc.(*Server).serveStreams.func2.1()
	google.golang.org/grpc@v1.72.1/server.go:1035 +0x7f
created by google.golang.org/grpc.(*Server).serveStreams.func2 in goroutine 40
	google.golang.org/grpc@v1.72.1/server.go:1046 +0x11d

Error: The terraform-provider-proxmox_v3.0.2-rc05 plugin crashed!

This is always indicative of a bug within the plugin. It would be immensely
helpful if you could report the crash with the plugin's maintainers so that it
can be fixed. The output above should help diagnose the issue.

Root Cause Analysis

The panic occurs when the provider attempts to convert nil interface values to strings without proper nil checking. This is a systemic issue affecting multiple parts of the codebase:

1. IDE Disk Devices (proxmox/config__qemu__disk__ide.go:108 in disksIde()):

   • When IDE devices are added but not fully active
   • The Proxmox API returns incomplete or nil values for certain IDE device properties
   • The provider attempts to convert these nil values to strings without checking

2. CPU Configuration (proxmox/config__qemu__cpu.go:629 in GetCPU()):

   • When CPU configuration is not fully active

3. General Configuration (proxmox/config__qemu.go:376 in mapToStruct()):

   • When any VM attribute is not fully active

The common pattern is that the provider does not handle nil values gracefully when parsing VM configuration from the Proxmox API. This is particularly problematic when:

• Components are added via terraform with "automatic_reboot = false" argument
• Components are added manually via Proxmox Web UI
• Components are in an incomplete/transitional state (yellow status in Proxmox)

Workaround

Temporary workarounds (depending on the affected component):

• Reboot the VM after adding the device, or remove the device before running terraform plan
• Remove manually added components that are in incomplete states

However, these workarounds are not ideal as they require manual intervention and defeat the purpose of infrastructure-as-code.

Additional Context

• This issue occurs when VM components are added or modified without VM reboot (shutdown & start) to implement the changes
• The issue does not occur if all components are fully active and properly configured
• The problem manifests when components are in an incomplete/transitional state (yellow status in Proxmox)
• This affects multiple areas: IDE disks, CPU config and potentially other VM attributes
• This is a regression/breaking issue that prevents normal Terraform operations

Related Issues

This appears to be related to similar nil pointer issues reported in:

• CPU configuration parsing (when CPU config is nil)

Stack trace from the terraform-provider-proxmox_v3.0.2-rc05 plugin:

panic: interface conversion: interface {} is nil, not string

goroutine 9 [running]:
github.com/Telmate/proxmox-api-go/proxmox.(*rawConfigQemu).GetCPU(0xc00100a100)
	github.com/Telmate/proxmox-api-go@v0.0.0-20251016192144-4a331a14ad5c/proxmox/config__qemu__cpu.go:629 +0x716
...

• Other cases (when other config is nil)

Stack trace from the terraform-provider-proxmox_v3.0.2-rc05 plugin:

panic: interface conversion: interface {} is nil, not string

goroutine 56 [running]:
github.com/Telmate/proxmox-api-go/proxmox.(*ConfigQemu).mapToStruct(0xc00025a1e0, 0xc000970640?, 0xc00164d410)
	github.com/Telmate/proxmox-api-go@v0.0.0-20251016192144-4a331a14ad5c/proxmox/config__qemu.go:376 +0x1485
...

The common pattern is that the provider does not handle nil values gracefully when parsing VM configuration from the Proxmox API.

Environment

• Proxmox Version: PVE 8.4.12
• Terraform Version: 1.13.4
• Provider Version: 3.0.2-rc05
• Operating System: AlmaLinux release 9.6 (Sage Margay)

[jambees]

I'm going to add this here as I think it's all related although with a different cause. In my case I was trying to clone a VM from a template whose disk was on a single cluster node's local storage and deploy to another node. Unsurprisingly it didn't work but it probably should be handled rather than a plugin crash and stack trace.

plugin version 3.0.2-rc05, Proxmox version 9.0.11

Here's the output from the terraform apply command:

proxmox_vm_qemu.dockertest_vm2: Creating...
proxmox_vm_qemu.dockertest_vm: Modifying... [id=proxmox1/qemu/111]
\u2577
\u2502 Error: Plugin did not respond
\u2502
\u2502 with proxmox_vm_qemu.dockertest_vm,
\u2502 on main.tf line 26, in resource "proxmox_vm_qemu" "dockertest_vm":
\u2502 26: resource "proxmox_vm_qemu" "dockertest_vm" {
\u2502
\u2502 The plugin encountered an error, and failed to respond to the plugin.(*GRPCProvider).ApplyResourceChange call. The plugin logs may contain more details.
\u2575
\u2577
\u2502 Error: error creating Guest: 500 can't clone VM to node 'proxmox2' (VM uses local storage), error status: {"message":"can't clone VM to node 'proxmox2' (VM uses local storage)\n","data":null} (params: map[full:true name:dockertest-node2 newid:112 target:proxmox2])
\u2502
\u2502 with proxmox_vm_qemu.dockertest_vm2,
\u2502 on main.tf line 93, in resource "proxmox_vm_qemu" "dockertest_vm2":
\u2502 93: resource "proxmox_vm_qemu" "dockertest_vm2" {
\u2502
\u2575

Stack trace from the terraform-provider-proxmox_v3.0.2-rc05 plugin:

panic: interface conversion: interface {} is nil, not string

goroutine 59 [running]:
github.com/Telmate/proxmox-api-go/proxmox.(*ConfigQemu).mapToStruct(0xc0001e3c20, 0xc000f834f0?, 0xc000c2e690)
github.com/Telmate/proxmox-api-go@v0.0.0-20251016192144-4a331a14ad5c/proxmox/config__qemu.go:398 +0x1414
github.com/Telmate/proxmox-api-go/proxmox.(*rawConfigQemu).get(0xc0009c6428, 0xc000f834f0)
github.com/Telmate/proxmox-api-go@v0.0.0-20251016192144-4a331a14ad5c/proxmox/config__qemu.go:1149 +0x4a5
github.com/Telmate/proxmox-api-go/proxmox.(*rawConfigQemu).Get(0xc0002ac1b0?, 0xf26a49?)
github.com/Telmate/proxmox-api-go@v0.0.0-20251016192144-4a331a14ad5c/proxmox/config__qemu.go:1123 +0x13
github.com/Telmate/terraform-provider-proxmox/v2/proxmox.resourceVmQemuRead({0x108b6d8, 0xc000235030}, 0xc0002ac1b0, {0xd6dea0?, 0xc000901130})
github.com/Telmate/terraform-provider-proxmox/v2/proxmox/resource_vm_qemu.go:997 +0x77c
github.com/Telmate/terraform-provider-proxmox/v2/proxmox.resourceVmQemuUpdate({0x108b6d8, 0xc000235030}, 0xc0002ac1b0, {0xd6dea0, 0xc000901130})
github.com/Telmate/terraform-provider-proxmox/v2/proxmox/resource_vm_qemu.go:948 +0x25f2
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*Resource).update(0xc000589900, {0x108b630, 0xc000dd8e70}, 0xc0002ac1b0, {0xd6dea0, 0xc000901130})
github.com/hashicorp/terraform-plugin-sdk/v2@v2.37.0/helper/schema/resource.go:883 +0x119
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*Resource).Apply(0xc000589900, {0x108b630, 0xc000dd8e70}, 0xc0009ec270, 0xc000f263f0, {0xd6dea0, 0xc000901130})
github.com/hashicorp/terraform-plugin-sdk/v2@v2.37.0/helper/schema/resource.go:990 +0x8f3
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*GRPCProviderServer).ApplyResourceChange(0xc00041e030, {0x108b630?, 0xc000dd82a0?}, 0xc000b04140)
github.com/hashicorp/terraform-plugin-sdk/v2@v2.37.0/helper/schema/grpc_provider.go:1484 +0x1085
github.com/hashicorp/terraform-plugin-go/tfprotov5/tf5server.(*server).ApplyResourceChange(0xc0002a6000, {0x108b630?, 0xc000dab950?}, 0xc0002a0300)
github.com/hashicorp/terraform-plugin-go@v0.28.0/tfprotov5/tf5server/server.go:941 +0x3b9
github.com/hashicorp/terraform-plugin-go/tfprotov5/internal/tfplugin5._Provider_ApplyResourceChange_Handler({0xefdb20, 0xc0002a6000}, {0x108b630, 0xc000dab950}, 0xc0002a0080, 0x0)
github.com/hashicorp/terraform-plugin-go@v0.28.0/tfprotov5/internal/tfplugin5/tfplugin5_grpc.pb.go:687 +0x1a6
google.golang.org/grpc.(*Server).processUnaryRPC(0xc000152c00, {0x108b630, 0xc000daae70}, 0xc000b08000, 0xc0006f70e0, 0x1729fe8, 0x0)
google.golang.org/grpc@v1.72.1/server.go:1405 +0x1036
google.golang.org/grpc.(*Server).handleStream(0xc000152c00, {0x108c010, 0xc000834000}, 0xc000b08000)
google.golang.org/grpc@v1.72.1/server.go:1815 +0xb88
google.golang.org/grpc.(*Server).serveStreams.func2.1()
google.golang.org/grpc@v1.72.1/server.go:1035 +0x7f
created by google.golang.org/grpc.(*Server).serveStreams.func2 in goroutine 36
google.golang.org/grpc@v1.72.1/server.go:1046 +0x11d

Error: The terraform-provider-proxmox_v3.0.2-rc05 plugin crashed!

[Tinyblargon]

@jambees based on github.com/Telmate/proxmox-api-go/proxmox.(*ConfigQemu).mapToStruct(0xc0001e3c20, 0xc000f834f0?, 0xc000c2e690) it crashes while trying to parse the json api response.

Could you give me the json config of the vm that you are cloning and the clone.

HTTP:   GET /api2/json/nodes/{node}/qemu/{vmid}/config

[jambees]

@jambees based on github.com/Telmate/proxmox-api-go/proxmox.(*ConfigQemu).mapToStruct(0xc0001e3c20, 0xc000f834f0?, 0xc000c2e690) it crashes while trying to parse the json api response.

Could you give me the json config of the vm that you are cloning and the clone.

HTTP:   GET /api2/json/nodes/{node}/qemu/{vmid}/config

Here's the JSON of the VM template I was trying to clone from wtih terraform as it stands now but things have moved on slightly from when i got the error as I have moved the disk and cdrom from local storage (local-lvm) to shared NFS storage.

{"data":{"template":1,"bootdisk":"scsi0","net0":"virtio=BC:24:11:43:9D:88,bridge=vmbr0","memory":"2048","serial0":"socket","boot":"c","smbios1":"uuid=219d84d6-3ee4-485e-a6fc-9fb265cf1c6a","ipconfig0":"ip=dhcp","cores":2,"name":"ubuntu-cloud","scsi0":"Proxmox_Templates_ISOs_NFS:9000/base-9000-disk-0.qcow2,size=2252M","ide2":"Proxmox_Templates_ISOs_NFS:9000/vm-9000-cloudinit.qcow2,media=cdrom","sshkeys":"[REDACTED]","cipassword":"**********","digest":"4459721605863887ae7d2cf2623fd81fb4ca2d62","meta":"creation-qemu=10.1.2,ctime=1762465566","vmgenid":"7dc1a10f-fa99-43d5-aa8c-0e7136151785","scsihw":"virtio-scsi-pci","ciuser":"ubuntu","vga":"serial0"}}

I can give you a JSON of a clone once I fixed my storage references so that deployment to different nodes worked in case that helps but as the deployments were failing with local storage references it wouldn't deploy. The below is from a VM deployed from the above template once I fixed storage locations.

{"data":{"agent":"1","boot":"order=scsi0","tablet":1,"numa":0,"meta":"creation-qemu=10.1.2,ctime=1762465566","memory":"2048","bios":"seabios","vmgenid":"99f2d301-76c6-4be2-bb77-f2412b4973a5","scsi0":"data2:vm-111-disk-0,discard=on,iothread=1,replicate=0,size=15G","serial0":"socket","kvm":1,"vga":"type=serial0","sshkeys":"[REDACTED]","protection":0,"ide3":"local-lvm:vm-111-cloudinit,media=cdrom","balloon":0,"onboot":0,"net0":"virtio=BC:24:11:DF:A5:7F,bridge=vmbr0","ipconfig0":"ip=dhcp","name":"dockertest-node2","scsihw":"virtio-scsi-single","description":"Managed by Terraform.","tags":" ","digest":"d40e4c90e6299a157086bfecef87d7100b8d170c","cores":2,"ciupgrade":0,"cpu":"host","hotplug":"network,disk,usb","sockets":1,"cicustom":"user=Proxmox_Templates_ISOs_NFS:snippets/cloud_init_test1.yml","smbios1":"uuid=93869260-10e3-4013-a870-3a8340189f34"}}

The test case for the error was create a VM template on one cluster node with the main boot drive and the cloud-init cdrom drive being in local-lvm on that node. Then in the terraform config file, create a VM that deploys to another node using that template. That caused the above errors when trying to apply the tf config file.

[jambees]

I just added a 3rd node to my proxmox cluster and so copied the vm definition in my terraform config one more time, edited the vm name and target node name and applied that. Was surprised it was saying it wanted to modify the 2 existing vms as well as create 1 new one but I let it continue. It has created the 3rd vm as intended on the correct node but a similar set of errors has been produced with the plugin crashing.

james@Terraform:~/Terraform/dockertest$ terraform apply
proxmox_vm_qemu.dockertest_vm: Refreshing state... [id=proxmox1/qemu/112]
proxmox_vm_qemu.dockertest_vm2: Refreshing state... [id=proxmox2/qemu/111]

Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
  + create
  ~ update in-place

Terraform will perform the following actions:

  # proxmox_vm_qemu.dockertest_vm will be updated in-place
  ~ resource "proxmox_vm_qemu" "dockertest_vm" {
        id                        = "proxmox1/qemu/112"
        name                      = "dockertest-node"
      - tags                      = " " -> null
        # (54 unchanged attributes hidden)

        # (6 unchanged blocks hidden)
    }

  # proxmox_vm_qemu.dockertest_vm2 will be updated in-place
  ~ resource "proxmox_vm_qemu" "dockertest_vm2" {
        id                        = "proxmox2/qemu/111"
        name                      = "dockertest-node2"
      - tags                      = " " -> null
        # (54 unchanged attributes hidden)

        # (6 unchanged blocks hidden)
    }

  # proxmox_vm_qemu.dockertest_vm3 will be created
  + resource "proxmox_vm_qemu" "dockertest_vm3" {
      + additional_wait           = 5
      + agent                     = 1
      + agent_timeout             = 90
      + automatic_reboot          = true
      + automatic_reboot_severity = "error"
      + balloon                   = 0
      + bios                      = "seabios"
      + boot                      = "order=scsi0"
      + bootdisk                  = (known after apply)
      + cicustom                  = "user=Proxmox_Templates_ISOs_NFS:snippets/cloud_init_test1.yml"
      + ciupgrade                 = false
      + clone                     = "ubuntu-cloud"
      + clone_wait                = 10
      + current_node              = (known after apply)
      + default_ipv4_address      = (known after apply)
      + default_ipv6_address      = (known after apply)
      + define_connection_info    = true
      + description               = "Managed by Terraform."
      + force_create              = false
      + full_clone                = true
      + hotplug                   = "network,disk,usb"
      + id                        = (known after apply)
      + ipconfig0                 = "ip=dhcp"
      + kvm                       = true
      + linked_vmid               = (known after apply)
      + memory                    = 2048
      + name                      = "dockertest-node3"
      + onboot                    = false
      + os_type                   = "cloud-init"
      + protection                = false
      + reboot_required           = (known after apply)
      + scsihw                    = "virtio-scsi-single"
      + skip_ipv4                 = false
      + skip_ipv6                 = true
      + ssh_host                  = (known after apply)
      + ssh_port                  = (known after apply)
      + sshkeys                   = <<-EOT
            [REDACTED]
        EOT
      + tablet                    = true
      + target_node               = "proxmox3"
      + unused_disk               = (known after apply)
      + vm_state                  = "running"
      + vmid                      = (known after apply)

      + cpu {
          + cores   = 2
          + limit   = 0
          + numa    = false
          + sockets = 1
          + type    = "host"
          + units   = 0
          + vcores  = 0
        }

      + disks {
          + ide {
              + ide3 {
                  + cloudinit {
                      + storage = "local-lvm"
                    }
                }
            }
          + scsi {
              + scsi0 {
                  + disk {
                      + backup               = true
                      + discard              = true
                      + format               = "raw"
                      + id                   = (known after apply)
                      + iops_r_burst         = 0
                      + iops_r_burst_length  = 0
                      + iops_r_concurrent    = 0
                      + iops_wr_burst        = 0
                      + iops_wr_burst_length = 0
                      + iops_wr_concurrent   = 0
                      + iothread             = true
                      + linked_disk_id       = (known after apply)
                      + mbps_r_burst         = 0
                      + mbps_r_concurrent    = 0
                      + mbps_wr_burst        = 0
                      + mbps_wr_concurrent   = 0
                      + size                 = "15G"
                      + storage              = "local-lvm"
                    }
                }
            }
        }

      + network {
          + bridge    = "vmbr0"
          + firewall  = false
          + id        = 0
          + link_down = false
          + macaddr   = (known after apply)
          + model     = "virtio"
        }

      + serial {
          + id   = 0
          + type = "socket"
        }

      + smbios (known after apply)

      + vga {
          + type = "serial0"
        }
    }

Plan: 1 to add, 2 to change, 0 to destroy.

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

proxmox_vm_qemu.dockertest_vm3: Creating...
proxmox_vm_qemu.dockertest_vm: Modifying... [id=proxmox1/qemu/112]
proxmox_vm_qemu.dockertest_vm2: Modifying... [id=proxmox2/qemu/111]
proxmox_vm_qemu.dockertest_vm3: Still creating... [00m10s elapsed]
proxmox_vm_qemu.dockertest_vm: Still modifying... [id=proxmox1/qemu/112, 00m10s elapsed]
proxmox_vm_qemu.dockertest_vm2: Still modifying... [id=proxmox2/qemu/111, 00m10s elapsed]
proxmox_vm_qemu.dockertest_vm3: Still creating... [00m20s elapsed]
proxmox_vm_qemu.dockertest_vm: Still modifying... [id=proxmox1/qemu/112, 00m20s elapsed]
proxmox_vm_qemu.dockertest_vm2: Still modifying... [id=proxmox2/qemu/111, 00m20s elapsed]
proxmox_vm_qemu.dockertest_vm3: Still creating... [00m30s elapsed]
proxmox_vm_qemu.dockertest_vm: Still modifying... [id=proxmox1/qemu/112, 00m30s elapsed]
proxmox_vm_qemu.dockertest_vm2: Still modifying... [id=proxmox2/qemu/111, 00m30s elapsed]
proxmox_vm_qemu.dockertest_vm3: Still creating... [00m40s elapsed]
proxmox_vm_qemu.dockertest_vm: Still modifying... [id=proxmox1/qemu/112, 00m40s elapsed]
proxmox_vm_qemu.dockertest_vm2: Still modifying... [id=proxmox2/qemu/111, 00m40s elapsed]
proxmox_vm_qemu.dockertest_vm3: Still creating... [00m50s elapsed]
proxmox_vm_qemu.dockertest_vm: Still modifying... [id=proxmox1/qemu/112, 00m50s elapsed]
proxmox_vm_qemu.dockertest_vm2: Still modifying... [id=proxmox2/qemu/111, 00m50s elapsed]
proxmox_vm_qemu.dockertest_vm3: Still creating... [01m00s elapsed]
proxmox_vm_qemu.dockertest_vm: Still modifying... [id=proxmox1/qemu/112, 01m00s elapsed]
proxmox_vm_qemu.dockertest_vm2: Still modifying... [id=proxmox2/qemu/111, 01m00s elapsed]
proxmox_vm_qemu.dockertest_vm3: Still creating... [01m10s elapsed]
proxmox_vm_qemu.dockertest_vm: Still modifying... [id=proxmox1/qemu/112, 01m10s elapsed]
proxmox_vm_qemu.dockertest_vm2: Still modifying... [id=proxmox2/qemu/111, 01m10s elapsed]
proxmox_vm_qemu.dockertest_vm3: Still creating... [01m20s elapsed]
proxmox_vm_qemu.dockertest_vm: Still modifying... [id=proxmox1/qemu/112, 01m20s elapsed]
proxmox_vm_qemu.dockertest_vm2: Still modifying... [id=proxmox2/qemu/111, 01m20s elapsed]
proxmox_vm_qemu.dockertest_vm3: Still creating... [01m30s elapsed]
proxmox_vm_qemu.dockertest_vm: Still modifying... [id=proxmox1/qemu/112, 01m30s elapsed]
proxmox_vm_qemu.dockertest_vm2: Still modifying... [id=proxmox2/qemu/111, 01m30s elapsed]
proxmox_vm_qemu.dockertest_vm3: Still creating... [01m40s elapsed]
proxmox_vm_qemu.dockertest_vm: Still modifying... [id=proxmox1/qemu/112, 01m40s elapsed]
proxmox_vm_qemu.dockertest_vm2: Still modifying... [id=proxmox2/qemu/111, 01m40s elapsed]
proxmox_vm_qemu.dockertest_vm3: Still creating... [01m50s elapsed]
proxmox_vm_qemu.dockertest_vm: Still modifying... [id=proxmox1/qemu/112, 01m50s elapsed]
proxmox_vm_qemu.dockertest_vm2: Still modifying... [id=proxmox2/qemu/111, 01m50s elapsed]
proxmox_vm_qemu.dockertest_vm3: Still creating... [02m00s elapsed]
proxmox_vm_qemu.dockertest_vm: Still modifying... [id=proxmox1/qemu/112, 02m00s elapsed]
proxmox_vm_qemu.dockertest_vm2: Still modifying... [id=proxmox2/qemu/111, 02m00s elapsed]
proxmox_vm_qemu.dockertest_vm3: Still creating... [02m10s elapsed]
proxmox_vm_qemu.dockertest_vm: Still modifying... [id=proxmox1/qemu/112, 02m10s elapsed]
proxmox_vm_qemu.dockertest_vm2: Still modifying... [id=proxmox2/qemu/111, 02m10s elapsed]
proxmox_vm_qemu.dockertest_vm3: Still creating... [02m20s elapsed]
proxmox_vm_qemu.dockertest_vm: Still modifying... [id=proxmox1/qemu/112, 02m20s elapsed]
proxmox_vm_qemu.dockertest_vm2: Still modifying... [id=proxmox2/qemu/111, 02m20s elapsed]
proxmox_vm_qemu.dockertest_vm3: Still creating... [02m30s elapsed]
proxmox_vm_qemu.dockertest_vm: Still modifying... [id=proxmox1/qemu/112, 02m30s elapsed]
proxmox_vm_qemu.dockertest_vm2: Still modifying... [id=proxmox2/qemu/111, 02m30s elapsed]
proxmox_vm_qemu.dockertest_vm3: Still creating... [02m40s elapsed]
proxmox_vm_qemu.dockertest_vm: Still modifying... [id=proxmox1/qemu/112, 02m40s elapsed]
proxmox_vm_qemu.dockertest_vm2: Still modifying... [id=proxmox2/qemu/111, 02m40s elapsed]
proxmox_vm_qemu.dockertest_vm3: Creation complete after 2m46s [id=proxmox3/qemu/113]
\u2577
\u2502 Error: Plugin did not respond
\u2502 
\u2502   with proxmox_vm_qemu.dockertest_vm,
\u2502   on main.tf line 26, in resource "proxmox_vm_qemu" "dockertest_vm":
\u2502   26: resource "proxmox_vm_qemu" "dockertest_vm" {
\u2502 
\u2502 The plugin encountered an error, and failed to respond to the plugin.(*GRPCProvider).ApplyResourceChange call. The plugin logs may contain more details.
\u2575
\u2577
\u2502 Error: Plugin did not respond
\u2502 
\u2502   with proxmox_vm_qemu.dockertest_vm2,
\u2502   on main.tf line 93, in resource "proxmox_vm_qemu" "dockertest_vm2":
\u2502   93: resource "proxmox_vm_qemu" "dockertest_vm2" {
\u2502 
\u2502 The plugin encountered an error, and failed to respond to the plugin.(*GRPCProvider).ApplyResourceChange call. The plugin logs may contain more details.
\u2575

Stack trace from the terraform-provider-proxmox_v3.0.2-rc05 plugin:

panic: interface conversion: interface {} is nil, not string

goroutine 16 [running]:
github.com/Telmate/proxmox-api-go/proxmox.(*ConfigQemu).mapToStruct(0xc0001783c0, 0xc000e96460?, 0xc0010937d0)
	github.com/Telmate/proxmox-api-go@v0.0.0-20251016192144-4a331a14ad5c/proxmox/config__qemu.go:398 +0x1414
github.com/Telmate/proxmox-api-go/proxmox.(*rawConfigQemu).get(0xc001b02e68, 0xc000e96460)
	github.com/Telmate/proxmox-api-go@v0.0.0-20251016192144-4a331a14ad5c/proxmox/config__qemu.go:1149 +0x4a5
github.com/Telmate/proxmox-api-go/proxmox.(*rawConfigQemu).Get(0xc001282ea0?, 0xf26a49?)
	github.com/Telmate/proxmox-api-go@v0.0.0-20251016192144-4a331a14ad5c/proxmox/config__qemu.go:1123 +0x13
github.com/Telmate/terraform-provider-proxmox/v2/proxmox.resourceVmQemuRead({0x108b6d8, 0xc00020e770}, 0xc001282ea0, {0xd6dea0?, 0xc00047ad20})
	github.com/Telmate/terraform-provider-proxmox/v2/proxmox/resource_vm_qemu.go:997 +0x77c
github.com/Telmate/terraform-provider-proxmox/v2/proxmox.resourceVmQemuUpdate({0x108b6d8, 0xc00020e770}, 0xc001282ea0, {0xd6dea0, 0xc00047ad20})
	github.com/Telmate/terraform-provider-proxmox/v2/proxmox/resource_vm_qemu.go:948 +0x25f2
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*Resource).update(0xc000257800, {0x108b630, 0xc000c54bd0}, 0xc001282ea0, {0xd6dea0, 0xc00047ad20})
	github.com/hashicorp/terraform-plugin-sdk/v2@v2.37.0/helper/schema/resource.go:883 +0x119
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*Resource).Apply(0xc000257800, {0x108b630, 0xc000c54bd0}, 0xc000a7a1a0, 0xc00104c360, {0xd6dea0, 0xc00047ad20})
	github.com/hashicorp/terraform-plugin-sdk/v2@v2.37.0/helper/schema/resource.go:990 +0x8f3
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*GRPCProviderServer).ApplyResourceChange(0xc00012e2d0, {0x108b630?, 0xc000c54b10?}, 0xc00024abe0)
	github.com/hashicorp/terraform-plugin-sdk/v2@v2.37.0/helper/schema/grpc_provider.go:1484 +0x1085
github.com/hashicorp/terraform-plugin-go/tfprotov5/tf5server.(*server).ApplyResourceChange(0xc000276000, {0x108b630?, 0xc000c54210?}, 0xc000176180)
	github.com/hashicorp/terraform-plugin-go@v0.28.0/tfprotov5/tf5server/server.go:941 +0x3b9
github.com/hashicorp/terraform-plugin-go/tfprotov5/internal/tfplugin5._Provider_ApplyResourceChange_Handler({0xefdb20, 0xc000276000}, {0x108b630, 0xc000c54210}, 0xc000176100, 0x0)
	github.com/hashicorp/terraform-plugin-go@v0.28.0/tfprotov5/internal/tfplugin5/tfplugin5_grpc.pb.go:687 +0x1a6
google.golang.org/grpc.(*Server).processUnaryRPC(0xc000382000, {0x108b630, 0xc000c54150}, 0xc0001167e0, 0xc00076b0e0, 0x1729fe8, 0x0)
	google.golang.org/grpc@v1.72.1/server.go:1405 +0x1036
google.golang.org/grpc.(*Server).handleStream(0xc000382000, {0x108c010, 0xc000858000}, 0xc0001167e0)
	google.golang.org/grpc@v1.72.1/server.go:1815 +0xb88
google.golang.org/grpc.(*Server).serveStreams.func2.1()
	google.golang.org/grpc@v1.72.1/server.go:1035 +0x7f
created by google.golang.org/grpc.(*Server).serveStreams.func2 in goroutine 36
	google.golang.org/grpc@v1.72.1/server.go:1046 +0x11d

Error: The terraform-provider-proxmox_v3.0.2-rc05 plugin crashed!

This is always indicative of a bug within the plugin. It would be immensely
helpful if you could report the crash with the plugin's maintainers so that it
can be fixed. The output above should help diagnose the issue.

JSON from the first 2 VMs and the newly created VM in case it helps you as they will match this run now:

Node 1, VM1

{"data":{"cpu":"host","balloon":0,"cores":2,"protection":0,"cicustom":"user=Proxmox_Templates_ISOs_NFS:snippets/cloud_init_test1.yml","ipconfig0":"ip=dhcp","smbios1":"uuid=69790041-5d80-4322-9c0b-d092ca0d0933","boot":"order=scsi0","onboot":0,"serial0":"socket","tags":" ","hotplug":"network,disk,usb","ciupgrade":0,"memory":"2048","agent":"1","kvm":1,"net0":"virtio=BC:24:11:8F:2A:62,bridge=vmbr0","scsihw":"virtio-scsi-single","vmgenid":"9c2a393e-875d-49aa-98b9-267d0b171899","numa":0,"vga":"type=serial0","scsi0":"local-lvm:vm-112-disk-0,discard=on,iothread=1,replicate=0,size=15G","sshkeys":"[REDACTED]","tablet":1,"name":"dockertest-node","meta":"creation-qemu=10.1.2,ctime=1762465566","digest":"a55d2896a0c8b33427145288fad7e7202009e282","sockets":1,"bios":"seabios","ide3":"local-lvm:vm-112-cloudinit,media=cdrom","description":"Managed by Terraform."}}

Node 2, VM2

{"data":{"bios":"seabios","memory":"2048","meta":"creation-qemu=10.1.2,ctime=1762465566","numa":0,"tablet":1,"boot":"order=scsi0","agent":"1","protection":0,"sshkeys":"[REDACTED]","kvm":1,"vga":"type=serial0","scsi0":"data2:vm-111-disk-0,discard=on,iothread=1,replicate=0,size=15G","serial0":"socket","vmgenid":"99f2d301-76c6-4be2-bb77-f2412b4973a5","cores":2,"digest":"0e75c94eaaee7216f09f0a655cee8136e4ccdd22","tags":" ","description":"Managed by Terraform.","scsihw":"virtio-scsi-single","name":"dockertest-node2","ipconfig0":"ip=dhcp","net0":"virtio=BC:24:11:DF:A5:7F,bridge=vmbr0","onboot":0,"balloon":0,"ide3":"local-lvm:vm-111-cloudinit,media=cdrom","smbios1":"uuid=93869260-10e3-4013-a870-3a8340189f34","cicustom":"user=Proxmox_Templates_ISOs_NFS:snippets/cloud_init_test1.yml","ostype":"other","hotplug":"network,disk,usb","cpu":"host","sockets":1,"ciupgrade":0}}

Node 3, VM3

{"data":{"net0":"virtio=BC:24:11:7A:A5:2A,bridge=vmbr0","agent":"1","smbios1":"uuid=d1e5d6d4-56ce-4107-a0f2-714ce6a29987","cpu":"host","protection":0,"serial0":"socket","cicustom":"user=Proxmox_Templates_ISOs_NFS:snippets/cloud_init_test1.yml","memory":"2048","hotplug":"network,disk,usb","balloon":0,"tags":" ","ipconfig0":"ip=dhcp","ciupgrade":0,"sshkeys":"[REDACTED]","kvm":1,"onboot":0,"sockets":1,"vga":"type=serial0","scsihw":"virtio-scsi-single","cores":2,"vmgenid":"7e72fb4b-84f6-46c6-9b89-dbe35e437b6d","meta":"creation-qemu=10.1.2,ctime=1762465566","scsi0":"local-lvm:vm-113-disk-0,discard=on,iothread=1,replicate=0,size=15G","bios":"seabios","digest":"9d754f8b32d737d90e6438b4c56f9155cc89d898","numa":0,"boot":"order=scsi0","name":"dockertest-node3","ide3":"local-lvm:vm-113-cloudinit,media=cdrom","description":"Managed by Terraform.","tablet":1}}

Terraform config file in case usefull:

terraform {
  required_providers {
    proxmox = {
      source  = "Telmate/proxmox"
      #version = "3.0.1-rc3" # Or latest available
      version = "3.0.2-rc05"
    }
  }
}

provider "proxmox" {
  pm_api_url = "https://10.12.1.36:8006/api2/json"

  pm_api_token_id = "terraform@pam!Terraform"
  pm_api_token_secret = "[REDACTED]"
  pm_tls_insecure = true           # if your Proxmox uses self-signed certs
}

resource "proxmox_vm_qemu" "dockertest_vm" {
  name        = "dockertest-node"
  target_node = "proxmox1"                 # Change to your Proxmox node name
  #clone       = "ubuntu-22.04-cloud"  # Your base cloud-init template name
  clone = "ubuntu-cloud"

  # Activate QEMU agent for this VM
  agent = 1
  
  os_type = "cloud-init"

  cpu {
        cores = 2
        sockets = 1
        type = "host"
  }
  memory      = 2048
  scsihw      = "virtio-scsi-single"

  vga {
        type = "serial0"
  }  
  serial {
        id = 0
        type = "socket"
  }

    disks {
        ide {
            ide3 {
                cloudinit {
                    storage = "local-lvm"
                }
            }
        }
        scsi {
            scsi0 {
                disk {
                    storage = "local-lvm"
                    size    = "15G"
                    discard = true
                    iothread = true
                }
            }
        }
    }

  network {
    id = 0
    model  = "virtio"
    bridge = "vmbr0"
  }

  boot = "order=scsi0"
  ipconfig0 = "ip=dhcp"
  #ipconfig0 = "ip=10.12.1.105/24,gw=10.12.1.1"
  skip_ipv6 = true
  sshkeys = file(pathexpand("~/Terraform/dockertest/.ssh/id_rsa.pub"))

  # Here's where Docker gets installed!
  # This runs on first boot inside the VM
  #cicustom = "user=local:snippets/user-data.yaml"
  
  #cicustom = "user=local:snippets/cloud_init_test1.yml"
  cicustom = "user=Proxmox_Templates_ISOs_NFS:snippets/cloud_init_test1.yml"
}

resource "proxmox_vm_qemu" "dockertest_vm2" {
  name        = "dockertest-node2"
  target_node = "proxmox2"                 # Change to your Proxmox node name
  #clone       = "ubuntu-22.04-cloud"  # Your base cloud-init template name
  clone = "ubuntu-cloud"

  # Activate QEMU agent for this VM
  agent = 1
  
  os_type = "cloud-init"

  cpu {
        cores = 2
        sockets = 1
        type = "host"
  }
  memory      = 2048
  scsihw      = "virtio-scsi-single"

  vga {
        type = "serial0"
  }  
  serial {
        id = 0
        type = "socket"
  }

    disks {
        ide {
            ide3 {
                cloudinit {
                    storage = "local-lvm"
                }
            }
        }
        scsi {
            scsi0 {
                disk {
                    storage = "data2"
                    size    = "15G"
                    discard = true
                    iothread = true
                }
            }
        }
    }

  network {
    id = 0
    model  = "virtio"
    bridge = "vmbr0"
  }

  boot = "order=scsi0"
  ipconfig0 = "ip=dhcp"
  #ipconfig0 = "ip=10.12.1.105/24,gw=10.12.1.1"
  skip_ipv6 = true
  sshkeys = file(pathexpand("~/Terraform/dockertest/.ssh/id_rsa.pub"))

  # Here's where Docker gets installed!
  # This runs on first boot inside the VM
  #cicustom = "user=local:snippets/user-data.yaml"
  
  #cicustom = "user=local:snippets/cloud_init_test1.yml"
  cicustom = "user=Proxmox_Templates_ISOs_NFS:snippets/cloud_init_test1.yml"
}

resource "proxmox_vm_qemu" "dockertest_vm3" {
  name        = "dockertest-node3"
  target_node = "proxmox3"                 # Change to your Proxmox node name
  #clone       = "ubuntu-22.04-cloud"  # Your base cloud-init template name
  clone = "ubuntu-cloud"

  # Activate QEMU agent for this VM
  agent = 1
  
  os_type = "cloud-init"

  cpu {
        cores = 2
        sockets = 1
        type = "host"
  }
  memory      = 2048
  scsihw      = "virtio-scsi-single"

  vga {
        type = "serial0"
  }  
  serial {
        id = 0
        type = "socket"
  }

    disks {
        ide {
            ide3 {
                cloudinit {
                    storage = "local-lvm"
                }
            }
        }
        scsi {
            scsi0 {
                disk {
                    storage = "local-lvm"
                    size    = "15G"
                    discard = true
                    iothread = true
                }
            }
        }
    }

  network {
    id = 0
    model  = "virtio"
    bridge = "vmbr0"
  }

  boot = "order=scsi0"
  ipconfig0 = "ip=dhcp"
  #ipconfig0 = "ip=10.12.1.105/24,gw=10.12.1.1"
  skip_ipv6 = true
  sshkeys = file(pathexpand("~/Terraform/dockertest/.ssh/id_rsa.pub"))

  # Here's where Docker gets installed!
  # This runs on first boot inside the VM
  #cicustom = "user=local:snippets/user-data.yaml"
  
  #cicustom = "user=local:snippets/cloud_init_test1.yml"
  cicustom = "user=Proxmox_Templates_ISOs_NFS:snippets/cloud_init_test1.yml"
}

[mitchross]

I have this same issue so tagging along to see outcome.