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To me it seems as it's expecting `InstanceRootBlockDeviceArgs` but you are passing a list of a single `InstanceRootBlockDeviceArgs`  in the code you posted. The definition does not seem to expect a list:
```root_block_device: Optional[pulumi.Input[pulumi.InputType['InstanceRootBlockDeviceArgs']]] = None,```


Thanks for replying and pointing me in the right direction. The issue was the subnet_id.