`JsonReaderException: Unterminated string` sending first DebugAdapter message

Hello

I’m trying to debug a .NET Core app over SSH on a Docker container that’s running on a remote server. I read your offroad debugging docs and learned a lot by trial and error talking to vsdbg. I’m able to run the plink/ssh command in a shell, paste a JSON message (with Content-Length; see picture) and get the remote app to talk back to me. However, when doing the same in Visual Studio 2019 the DebugAdapter throws a JsonReaderException and often doesn’t send any data to the remote (but sometimes it does send!).

Here’s my launch.json, the comments are for my team:

// This is for anyone working in Visual Studio to debug _remote_ Docker
// containers via SSH to ca-vic-app01 in QA
// View->Other Windows->Command Window
// DebugAdapterHost.Logging /On /OutputWindow
// DebugAdapterHost.Launch /LaunchJson:"<THIS FILE.json>" /EngineGuid:541B8A8A-6081-4506-9F0A-1CE771DEBC04
{
	// Docs on launch.json:
	// https://github.com/Microsoft/MIEngine/wiki/Offroad-Debugging-of-.NET-Core-on-Linux---OSX-from-Visual-Studio
	"version": "0.2.0",
	"adapter": "C:\\Program Files\\PuTTY\\plink.exe",
	// Change the container name here. Must be built with debugging symbols and
	// include the remote debugger via bind mount or the Dockerfile
	"adapterArgs": "-i \"C:\\id.ppk\" user@ca-vic-app01 -t -batch docker attach maestro-api-debug-vsdbg",
	"configurations": [
		{
			"name": ".NET Core Remote Docker Attach",
			"type": "coreclr",
			"request": "attach",
			"processId": 1
		}
	]
}
// If you just want to do local Docker debugging, install this:
// https://marketplace.visualstudio.com/items?itemName=Dreamescaper.AttachToDockerContainer

I’m running these in the command window:

>DebugAdapterHost.Logging /On /OutputWindow /Verbosity:debug
>DebugAdapterHost.Launch /LaunchJson:"C:\Projects\EFX\launch.json" /EngineGuid:541B8A8A-6081-4506-9F0A-1CE771DEBC04

I get a pop up of the error and this output:

 1> DebugAdapterHost version: 16.0.30220.2 commit:37bf7cc091107568bd6aa14b6229bb6741ce945f
 1> State: Unset => Initializing
 1> Sending VS event: IDebugEngineCreateEvent2 (fe5b734c-759d-4e59-ab04-f103343bdd06)
 1> Sending VS event: IDebugProgramCreateEvent2 (96cd11ee-ecd4-4e89-957e-b5d496fc4139)
 1> Starting 'C:\Program Files\PuTTY\plink.exe' with arguments '-i "C:\id.ppk" user@ca-vic-app01 -t -batch docker attach maestro-api-debug-vsdbg'
 1> [DebugAdapter] --> C (initialize-1): {"command":"initialize","arguments":{"clientID":"visualstudio","clientName":"Visual Studio","adapterID":"coreclr","locale":"en-US","linesStartAt1":true,"columnsStartAt1":true,"pathFormat":"path","supportsVariableType":true,"supportsRunInTerminalRequest":true,"supportsHandshakeRequest":true},"seq":1,"type":"request"}
 1> WARNING: Stopping due to fatal error: JsonReaderException: Unterminated string. Expected delimiter: ". Path 'type', line 3, position 313.
 1> Cancelling outstanding request(s) with ID(s): 1
 1> ERROR: Debug Adapter did not respond to initial requests.
 1> ERROR: Unexpected error

AggregateException: One or more errors occurred.

Aggregate exception: 
    DebugAdapterLaunchException: Failed to launch debug adapter.  Additional information may be available in the output window.

    Failure Location: UserCanceled
    Inner Exception: 
        OperationCanceledException: The operation was canceled.
Inner Exception: 
    DebugAdapterLaunchException: Failed to launch debug adapter.  Additional information may be available in the output window.

Microsoft.VisualStudio.Debugger.VSCodeDebuggerHost.Engine.Implementation.DebuggedProcess.<StartDebugAdapter>b__91_1(Exception ex)
Microsoft.VisualStudio.Debugger.VSCodeDebuggerHost.Utilities.TaskExtensions.<>c__DisplayClass11_0`1.<Catch>b__0(TException ex)
Microsoft.VisualStudio.Debugger.VSCodeDebuggerHost.Utilities.TaskExtensions.<>c__DisplayClass10_0`1.<Catch>b__0(AggregateException ex)

    Failure Location: UserCanceled
    Inner Exception: 
        OperationCanceledException: The operation was canceled.

 1> ERROR: One or more errors occurred.

Failed to launch debug adapter.  Additional information may be available in the output window.

The operation was canceled.
 1> Sending VS event: IDebugErrorEvent2 (fdb7a36c-8c53-41da-a337-8bd86b14d5cb)
 1> State: Initializing => Exiting
 1> State: Exiting => Exited
 1> Sending VS event: IDebugProgramDestroyEvent2 (e147e9e3-6440-4073-a7b7-a65592c714b5)
 1> ERROR: Unexpected error

JsonReaderException: Unterminated string. Expected delimiter: ". Path 'type', line 3, position 313.

Newtonsoft.Json.JsonTextReader.ReadStringIntoBuffer(Char quote)
Newtonsoft.Json.JsonTextReader.ParseString(Char quote, ReadType readType)
Newtonsoft.Json.JsonTextReader.ParseValue()
Newtonsoft.Json.JsonTextReader.Read()
Newtonsoft.Json.Serialization.JsonSerializerInternalReader.ReadForType(JsonReader reader, JsonContract contract, Boolean hasConverter)
Newtonsoft.Json.Serialization.JsonSerializerInternalReader.ResolvePropertyAndCreatorValues(JsonObjectContract contract, JsonProperty containerProperty, JsonReader reader, Type objectType)
Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObjectUsingCreatorWithParameters(JsonReader reader, JsonObjectContract contract, JsonProperty containerProperty, ObjectConstructor`1 creator, String id)
Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateNewObject(JsonReader reader, JsonObjectContract objectContract, JsonProperty containerMember, JsonProperty containerProperty, String id, Boolean& createdFromNonDefaultCreator)
Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateObject(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
Newtonsoft.Json.Serialization.JsonSerializerInternalReader.CreateValueInternal(JsonReader reader, Type objectType, JsonContract contract, JsonProperty member, JsonContainerContract containerContract, JsonProperty containerMember, Object existingValue)
Newtonsoft.Json.Serialization.JsonSerializerInternalReader.Deserialize(JsonReader reader, Type objectType, Boolean checkAdditionalContent)
Newtonsoft.Json.JsonSerializer.DeserializeInternal(JsonReader reader, Type objectType)
Newtonsoft.Json.JsonConvert.DeserializeObject(String value, Type type, JsonSerializerSettings settings)
Newtonsoft.Json.JsonConvert.DeserializeObject[T](String value, JsonSerializerSettings settings)
Microsoft.VisualStudio.Shared.VSCodeDebugProtocol.Protocol.DebugProtocol.HandleIncomingMessage(String msg)
Microsoft.VisualStudio.Shared.VSCodeDebugProtocol.Protocol.DebugProtocol.ProcessMessageBody()
Microsoft.VisualStudio.Shared.VSCodeDebugProtocol.Protocol.DebugProtocol.ReaderThreadProc()

 1> ERROR: Unterminated string. Expected delimiter: ". Path 'type', line 3, position 313.
 1> Sending VS event: IDebugErrorEvent2 (fdb7a36c-8c53-41da-a337-8bd86b14d5cb)
 1> Debug adapter process exited.
 1> Debug adapter non-protocol standard output: st"}

It says it’s “user canceled” but I’m not touching anything else after running it.

I’m using docker attach in my launch.json above, but the issue also happens for docker exec -it /opt/vsdbg/vsdbg --interpreter=vscode or even on the Linux host with /home/user/vsdbg/vsdbg --interpreter=vscode. I don’t think it’s an issue on the remote, I think it’s in VS2019/DebugAdapter…

The DebugAdapter always throws an error, but sometimes (once or twice) the message is sent before it crashes, and this is what I see:

Which is valid JSON! So I’m not sure why it thinks the st" is being cut off. Although I was concerned if it had to do with the Content-Length header and then have 3 newlines in the output? Might not be related.

I didn’t see any issues about this, or JSON, or unterminated strings in this repo or Omnisharp’s. Have you seen something like this before?

Thanks for all your work into this project!

[paulmaybee]

I’m not familiar with your scenario at all, but looking at your json it looks like this line is improperly formatted. It looks like it is missing a ‘\’ after the “ppk”.

              "adapterArgs": "-i \"C:\\id.ppk" user@ca-vic-app01 -t -batch docker attach maestro-api-debug-vsdbg",

[gregg-miskelly]

Thanks! I made a few tweaks and merged in your changes.