Unable to connect to remote server (ENOTFOUND).

Description

Environment

VS Code version:

Version: 1.105.1 (Universal)
Commit: 7d842fb85a0275a4a8e4d7e040d2625abbf7f084
Date: 2025-10-14T22:33:36.618Z
Electron: 37.6.0
ElectronBuildId: 12502201
Chromium: 138.0.7204.251
Node.js: 22.19.0
V8: 13.8.258.32-electron.0
OS: Darwin x64 24.6.0

Colab extension version: Latest available 0.1.0
Jupyter extension version: Identifier Version 2025.9.1
OS (Linux | Mac | Windows): OS: Darwin x64 24.6.0

Repro Steps

I connected to a Colab Notebook yesterday using an stable network connection. Opened Notebook (BigQuery basics.ipynb) and was able to execute code correctly
Today I reopened my Notebook and attempted to connect on my Hotel connection.

Notebook showed "Select Kernel"
Click on Select Kernel and then "Auto connect" nothing happened.
I just saw Kernel option back to "Select Kernel" no error displayed

At some point previous kernel (from yesterday showed Python 3), which led me to believe connection worked. Not sure if it we stored the previous successful connection.
I noticed some DNS errors when connecting to a different page.

Expected Behaviour

Display connection error

Actual Behaviour

Not error or warning, returns back to Select Kernel

Additional context

Logs

Logs from Colab in the Output panel (View > Output, change the drop-down the upper-right of the Output panel to Colab).

22:50:50.987 [debug] Start refreshing Kernel Picker (1763016650986)
22:50:51.045 [info] Switch kernel did not change kernel.
22:50:51.102 [debug] Controller selection change completed
22:50:51.215 [error] UniversalRemoteKernelFinder: Failed to get kernels without cache Od [Error]: request to https://colab.research.google.com/tun/m/assignments?authuser=0 failed, reason: getaddrinfo ENOTFOUND colab.research.google.com
    at un.getJupyterServerUri (~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:181:27882)
    at processTicksAndRejections (node:internal/process/task_queues:105:5)
    at un.createConnectionInfo (~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:181:25611)
    at ~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:279:17913 {
  category: 'remotejupyterserveruriprovider',
  isJupyterError: true,
  serverProviderHandle: {
    id: 'colab',
    handle: '7c3bfbab-36ff-4868-84f1-32a46a36e9aa',
    extensionId: 'google.colab'
  },
  originalError: Re [FetchError]: request to https://colab.research.google.com/tun/m/assignments?authuser=0 failed, reason: getaddrinfo ENOTFOUND colab.research.google.com
      at ClientRequest.<anonymous> (~/.vscode/extensions/google.colab-0.1.0/out/extension.js:1:308091)
      at ClientRequest.emit (node:events:531:35)
      at emitErrorEvent (node:_http_client:105:11)
      at TLSSocket.socketErrorListener (node:_http_client:518:5)
      at TLSSocket.emit (node:events:519:28)
      at emitErrorNT (node:internal/streams/destroy:170:8)
      at emitErrorCloseNT (node:internal/streams/destroy:129:3)
      at processTicksAndRejections (node:internal/process/task_queues:90:21) {
    type: 'system',
    errno: 'ENOTFOUND',
    code: 'ENOTFOUND'
  }
}
22:50:51.315 [debug] End refreshing Kernel Picker (1763016650986)
22:54:22.551 [debug] Handle Execution of Cells 2 for ~/Downloads/BigQuery basics.ipynb
22:54:22.584 [error] Error in notebook cell execution Error: notebook controller is DISPOSED
    at Object.createNotebookCellExecution (file:///Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/node/extensionHostProcess.js:201:21174)
    at n.create (~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:172:1856)
    at n.getOrCreate (~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:172:1647)
    at n.createCellExecutionIfNecessary (~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:309:93773)
    at ~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:309:94569
    at Array.forEach (<anonymous>)
    at n.executeQueuedCells (~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:309:94546)
    at n.handleExecution (~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:309:91402)
    at r4.$executeCells (file:///Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/node/extensionHostProcess.js:201:24241)
22:55:21.708 [debug] Handle Execution of Cells 2 for ~/Downloads/BigQuery basics.ipynb
22:55:21.708 [error] Error in notebook cell execution Error: notebook controller is DISPOSED
    at Object.createNotebookCellExecution (file:///Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/node/extensionHostProcess.js:201:21174)
    at n.create (~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:172:1856)
    at n.getOrCreate (~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:172:1647)
    at n.createCellExecutionIfNecessary (~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:309:93773)
    at ~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:309:94569
    at Array.forEach (<anonymous>)
    at n.executeQueuedCells (~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:309:94546)
    at n.handleExecution (~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:309:91402)
    at r4.$executeCells (file:///Applications/Visual%20Studio%20Code.app/Contents/Resources/app/out/vs/workbench/api/node/extensionHostProcess.js:201:24241)
23:02:27.604 [warn] Deleting controller dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..julia./usr/local/bin/julia././usr/local/bin/julia#-i#--color=yes#-e#import ijulia; ijulia.run_kernel()#{connection_file} as it is associated with a server Id that has been removed
23:02:27.605 [debug] Disposing controller dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..julia./usr/local/bin/julia././usr/local/bin/julia#-i#--color=yes#-e#import ijulia; ijulia.run_kernel()#{connection_file} associated with connection dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..julia./usr/local/bin/julia././usr/local/bin/julia#-i#--color=yes#-e#import ijulia; ijulia.run_kernel()#{connection_file} 
23:02:27.617 [warn] Deleting controller dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..julia./usr/local/bin/julia././usr/local/bin/julia#-i#--color=yes#-e#import ijulia; ijulia.run_kernel()#{connection_file} (Interactive) as it is associated with a server Id that has been removed
23:02:27.617 [debug] Disposing controller dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..julia./usr/local/bin/julia././usr/local/bin/julia#-i#--color=yes#-e#import ijulia; ijulia.run_kernel()#{connection_file} (Interactive) associated with connection dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..julia./usr/local/bin/julia././usr/local/bin/julia#-i#--color=yes#-e#import ijulia; ijulia.run_kernel()#{connection_file} 
23:02:27.617 [warn] Deleting controller dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..python3./usr/bin/python3./.-m#colab_kernel_launcher as it is associated with a server Id that has been removed
23:02:27.618 [debug] Disposing controller dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..python3./usr/bin/python3./.-m#colab_kernel_launcher associated with connection dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..python3./usr/bin/python3./.-m#colab_kernel_launcher and documents file://~/Downloads/BigQuery%20basics.ipynb
23:02:27.619 [warn] Deleting controller dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..python3./usr/bin/python3./.-m#colab_kernel_launcher (Interactive) as it is associated with a server Id that has been removed
23:02:27.619 [debug] Disposing controller dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..python3./usr/bin/python3./.-m#colab_kernel_launcher (Interactive) associated with connection dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..python3./usr/bin/python3./.-m#colab_kernel_launcher 
23:02:27.619 [warn] Deleting controller dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..ir./usr/lib/R/bin/R././usr/lib/r/bin/r#--slave#-e#irkernel::main()#--args#{connection_file} as it is associated with a server Id that has been removed
23:02:27.619 [debug] Disposing controller dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..ir./usr/lib/R/bin/R././usr/lib/r/bin/r#--slave#-e#irkernel::main()#--args#{connection_file} associated with connection dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..ir./usr/lib/R/bin/R././usr/lib/r/bin/r#--slave#-e#irkernel::main()#--args#{connection_file} 
23:02:27.619 [warn] Deleting controller dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..ir./usr/lib/R/bin/R././usr/lib/r/bin/r#--slave#-e#irkernel::main()#--args#{connection_file} (Interactive) as it is associated with a server Id that has been removed
23:02:27.619 [debug] Disposing controller dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..ir./usr/lib/R/bin/R././usr/lib/r/bin/r#--slave#-e#irkernel::main()#--args#{connection_file} (Interactive) associated with connection dc4052d47eca844c7b80f38963f52be4a49d3832e336d5a0f511bd989be07191..ir./usr/lib/R/bin/R././usr/lib/r/bin/r#--slave#-e#irkernel::main()#--args#{connection_file}

Logs from Jupyter in the Output panel (View > Output, change the drop-down the upper-right of the Output panel to Jupyter).

N/A

I tried to connect again using "Auto connect" and now I see correct message:
"Unable to connect to the remote server" Ensure the server is running and reachable.

23:11:41.699 [debug] Start refreshing Kernel Picker (1763017901699)
23:11:41.713 [info] Switch kernel did not change kernel.
23:11:41.739 [debug] Controller selection change completed
23:11:42.090 [error] Error fetching kernels from https://8080-m-s-3vdl0w8k5hame-a.asia-east1-1.prod.colab.dev/ (Colab CPU): FetchError: request to https://8080-m-s-3vdl0w8k5hame-a.asia-east1-1.prod.colab.dev/api/kernels?1763017902027 failed, reason: getaddrinfo ENOTFOUND 8080-m-s-3vdl0w8k5hame-a.asia-east1-1.prod.colab.dev
    at ClientRequest.<anonymous> (~/.vscode/extensions/google.colab-0.1.0/out/extension.js:1:308091)
    at ClientRequest.emit (node:events:531:35)
    at emitErrorEvent (node:_http_client:105:11)
    at TLSSocket.socketErrorListener (node:_http_client:518:5)
    at TLSSocket.emit (node:events:519:28)
    at emitErrorNT (node:internal/streams/destroy:170:8)
    at emitErrorCloseNT (node:internal/streams/destroy:129:3)
    at processTicksAndRejections (node:internal/process/task_queues:90:21)
23:11:42.101 [error] Jupyter Lab Helper:getKernelSpecs failure:  Error: Poll (@jupyterlab/services:KernelSpecManager#specs) is disposed.
    at i.dispose (~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/node_modules/@jupyterlab/services/index.js:11:35847)
    at Kr.dispose (~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/node_modules/@jupyterlab/services/index.js:11:75387)
    at ~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:181:22619
    at processTicksAndRejections (node:internal/process/task_queues:105:5)
23:11:44.032 [error] UniversalRemoteKernelFinder: Failed to get kernels without cache Od [Error]: request to https://colab.research.google.com/tun/m/assignments?authuser=0 failed, reason: getaddrinfo ENOTFOUND colab.research.google.com
    at un.getJupyterServerUri (~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:181:27882)
    at processTicksAndRejections (node:internal/process/task_queues:105:5)
    at un.createConnectionInfo (~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:181:25611)
    at ~/.vscode/extensions/ms-toolsai.jupyter-2025.9.1-darwin-x64/dist/extension.node.js:279:17913 {
  category: 'remotejupyterserveruriprovider',
  isJupyterError: true,
  serverProviderHandle: {
    id: 'colab',
    handle: '6d3a30d2-6af2-4b13-a931-b4ebf084580b',
    extensionId: 'google.colab'
  },
  originalError: Re [FetchError]: request to https://colab.research.google.com/tun/m/assignments?authuser=0 failed, reason: getaddrinfo ENOTFOUND colab.research.google.com
      at ClientRequest.<anonymous> (~/.vscode/extensions/google.colab-0.1.0/out/extension.js:1:308091)
      at ClientRequest.emit (node:events:531:35)
      at emitErrorEvent (node:_http_client:105:11)
      at TLSSocket.socketErrorListener (node:_http_client:518:5)
      at TLSSocket.emit (node:events:519:28)
      at emitErrorNT (node:internal/streams/destroy:170:8)
      at emitErrorCloseNT (node:internal/streams/destroy:129:3)
      at processTicksAndRejections (node:internal/process/task_queues:90:21) {
    type: 'system',
    errno: 'ENOTFOUND',
    code: 'ENOTFOUND'
  }
}
23:11:44.083 [debug] End refreshing Kernel Picker (1763017901699)

But seems to be different URL: https://colab.research.google.com/tun/m/assignments?authuser=0 (No error) vs https://8080-m-s-3vdl0w8k5hame-a.asia-east1-1.prod.colab.dev/ (Error is displayed)

Teasing this apart, I believe we're looking at two different bugs.

In the original issue, you can spot Error: notebook controller is DISPOSED. That's certainly another case of #200. We're still hard blocked on that (see discussion / links to open Jupyter issue(s)/PR).

But I won't close this as a duplicate, since the second stack indicates a different bug we can fix!

The issue is best summarized by this log (abbreviated for readability): Error fetching kernels from https://8080-[...]prod.colab.dev/: FetchError: request [...] failed, reason: getaddrinfo ENOTFOUND [...].

What we're seeing here is that Jupyter is trying to do background calls to fetch the kernels on an endpoint that's no longer available (ENOTFOUND). Off the top of my head, I can think of two possible reasons:

Jupyter is holding onto some cached kernel reference after a servers changed event has fired.
There's a race between the synchronous servers changed event and Jupyter requesting it.
Or, more likely, there's a race between us reconciling a server change.

To address the last possibility, one nifty thing we could do would be to wrap the server's overridden fetch requests (which are affinitized to a particular server) with middleware that detects these not-found results. When one is detected, trigger reconcileServers to prune the server which is no longer available.

I'll re-purpose this issue to track the latter, since the notebook controller is DISPOSED issue is already tracked in the aforementioned issue - #200.

error still not resolved

@MeetInCode

@MeetInCode the partial fix outlined in my last comment hasn't yet been developed.

If you do have consistent repro steps that land you in the state you screenshot, please do pass them along here. Ideally starting from a clean state (started by restarting VS Code).

Thanks a bunch for any and all help 🙏 !

@amtoney524

I think there's a small chance VS Code's recently used cache in the kernel selector could be causing this. Unsure.

@amtoney524 do you have cycles to add the ENOTFOUND detection logic detailed above?

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Unable to connect to remote server (ENOTFOUND). #206

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Unable to connect to remote server (ENOTFOUND). #206

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gogasca commented on Nov 13, 2025

kevineger commented on Nov 17, 2025

MeetInCode commented on Nov 17, 2025

kevineger commented on Nov 17, 2025

kevineger commented on Nov 21, 2025

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