Error with notebook debugging is vs code.

[TobiasKon]

Hi,

I’m trying to debug Fabric notebooks in VS Code, but keep running into problems.  It does work running the notebook normally using remote compute. 

I’ve followed the Microsoft Learn tutorials for debugging notebooks with the vscode extension and debugging with VS Code web experience , but every time I try to debug, VS Code just hangs with the message:

Initializing Fabric Data Engineering PySpark debug session. This can take a few minutes.

I’ve left it running for over an hour with no progress.

I checked the VS Code logs and saw this error:

2025-08-29 13:54:03.711 [error] [Window] [Extension Host] "TELEMETRY", {}, "event.websocketConnectionError", {"properties":{"name":"event.websocketConnectionError","errorName":"Error","errorMessage":"debug_request initialize cannot return within a certain time. Please try again. The msg_id is 431d5d17-1ada-4364-8bf7-e7055679550b.","errorStack":"Error: debug_request initialize cannot return within a certain time. Please try again. The msg_id is 431d5d17-1ada-4364-8bf7-e7055679550b.\n at c:\\Users\\tgk\\.vscode\\extensions\\synapsevscode.vscode-synapse-remote-0.9.0\\dist\\extension-node\\index.bundle.js:84396:136\n at c:\\Users\\tgk\\.vscode\\extensions\\synapsevscode.vscode-synapse-remote-0.9.0\\dist\\extension-node\\index.bundle.js:84233:78\n at Array.map (<anonymous>)\n at c:\\Users\\tgk\\.vscode\\extensions\\synapsevscode.vscode-synapse-remote-0.9.0\\dist\\extension-node\\index.bundle.js:84233:64\n at processTicksAndRejections (node:internal/process/task_queues:105:5)","tenantId":"7c2da93e-cc41-4f85-94d2-a124c32f9b32","custom.replyMsgId":"431d5d17-1ada-4364-8bf7-e7055679550b"}}

I also tried the VS Code extension with Docker image, but got stuck at the container build step.

I am using Windows, Visual Studio Code 1.103.2, and the 1.3 Spark Fabric runtime environment. I am using my work computer, so I have restricted access to administrator privileges, it could be an issue with my companys firewall, but don't know how to debug this issue.

Any tips, help to debug the issue, or workarounds would be greatly appreciated!

[v-hashadapu]

Hi @TobiasKon , hope you are doing great. May we know if your issue is solved or if you are still experiencing difficulties. Please share the details as it will help the community, especially others with similar issues.

[TobiasKon]

Hi @v-hashadapu, 
It is still not working. I have tried validating my install mutiple times now and it does still not work,  furthermore I am no longer able to run code from VS-code when not using debug mode. 

[v-hashadapu]

Hi @TobiasKon , Thank you for reaching out to the Microsoft Community Forum.

The only way forward I see is a full clean reset. Wipe all Fabric/Synapse extensions and their cached folders, make sure you have a proper JDK 8 (not just JRE), Conda on PATH and the Jupyter extension installed, then reinstall only the Fabric Data Engineering extension (use the pre-release build if the stable one keeps breaking). After signing back into Fabric in VS Code and setting a workspace, you should see the synapse-spark-kernel show up, without that, debugging simply can’t work.

If it still doesn’t appear, the issue is likely with the extension version itself, in which case raising a Microsoft Support ticket or raising a new issue in Github/Microsot issues is the best course of action.

[TobiasKon]

Hi @v-hashadapu,

Thank you for your response.

Thank you for your response.
I tried running the VS Code debugger while connected to a personal hotspot, and I now get a different error. The popup still shows:

Initializing Fabric Data Engineering PySpark debug session. This can take a few minutes.

But in the logs I see:

2025-09-01 09:18:17.181 [error] Error: command 'synapse-remote.internal.extensionIsReady' not found at kKe.n (vscode-file://vscode-app/c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:1251:3892) at kKe.executeCommand (vscode-file://vscode-app/c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:1251:3824) 2025-09-01 09:18:34.742 [error] TypeError: Cannot read properties of undefined (reading 'split') at Object.provideFileDecoration (c:\Users\tgk\.vscode\extensions\synapsevscode.synapse-1.15.0\dist\extension\extension.js:210581:41) at file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:119:4588 at Array.map (<anonymous>) at xy.$provideDecorations (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:119:4524) at C4.S (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:119615) at C4.Q (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:119395) at C4.M (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:118446) at C4.L (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:117589) at Jh.value (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:116386) at $.C (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2373) at $.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2591) at fo.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:9458) at Jh.value (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:388:8361) at $.C (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2373) at $.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2591) at fo.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:9458) at MessagePortMain.<anonymous> (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:388:6653) at MessagePortMain.emit (node:events:518:28) at Object.MessagePortMain._internalPort.emit (node:electron/js2c/utility_init:2:2949) 2025-09-01 09:19:07.622 [error] ExtensionError: Error in extension synapsevscode.vscode-synapse-remote: FAILED to handle event at Jh.value (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:196:100366) at $.C (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2373) at $.D (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2443) at $.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2660) at Jh.value (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:196:62698) at $.C (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2373) at $.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2591) at Cy.acceptDocumentsAndEditorsDelta (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:120:11788) at Cy.$acceptDocumentsAndEditorsDelta (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:120:10247) at C4.S (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:119615) at C4.Q (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:119395) at C4.M (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:118484) at C4.L (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:117589) at Jh.value (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:116386) at $.C (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2373) at $.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2591) at fo.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:9458) at Jh.value (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:388:8361) at $.C (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2373) at $.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2591) at fo.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:9458) at MessagePortMain.<anonymous> (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:388:6653) at MessagePortMain.emit (node:events:518:28) at Object.MessagePortMain._internalPort.emit (node:electron/js2c/utility_init:2:2949)

And it still does not work.
Also I don't see the synapse-spark-kernel  kernel, I see Microsoft Runtime into a pyspark kernel 

Do you get any leads, to what the issue might be? 

[v-hashadapu]

 Hi @TobiasKon , Thank you for reaching out to the Microsoft Community Forum.

The errors you’re seeing now come from conflicting or corrupted Fabric/Synapse extensions in VS Code, not from the network. That’s why you get messages like extensionIsReady not found and why only the Microsoft Runtime PySpark kernel shows up instead of the proper synapse-spark-kernel. When the wrong extension loads, the debugger can’t initialize.

Uninstall all Synapse/Fabric extensions from VS Code, delete their folders under your .vscode/extensions directory, then reinstall just the Fabric Data Engineering (Preview) extension. After reinstall, sign back into Fabric in VS Code, that should refresh the environment and surface the correct Spark kernel so debugging can start normally.

[TobiasKon]

Hi @v-hashadapu,

Thanks once again for your reply. I have now tried following your instructions, by uninstalling all fabric related vs code extensions. It still does not work, I am still only able to see the Microsoft Runtime PySpark kernel, and the debugging does not work. 

I don't see the error: "ExtensionIsReady not found" anymore.

But I still get the error:

[error] TypeError: Cannot read properties of undefined (reading 'split')

I don't have the Fabric Data Engineering (Preview) extension avaliable to me, only the Fabric Data Engineering extension, should I try with the pre-release version of the extension? 

[v-hashadapu]

Hi @TobiasKon , Thank you for reaching out to the Microsoft Community Forum.

This may mean the Fabric VS Code desktop extension isn’t fully setting itself up. On desktop it needs OpenJDK 8 (JDK, not JRE), Conda and the Jupyter extension, with JAVA_HOME and PATH pointing to that JDK. Once those are installed, reinstall the Fabric Data Engineering (desktop) extension, set a local work folder through its command, sign in and select your Fabric workspace. That should make the synapse-spark-kernel show up, without it, debugging won’t run. If it still errors, try the extension’s pre-release build, which fixes the crash in newer versions.

Solved: Re: VS Code and Synapse Kernel - Microsoft Fabric Community

Solved: Can't start kernel from notebook in VS Code synaps... - Microsoft Fabric Community

Create and manage Fabric notebooks from VS Code for the Web - Microsoft Fabric | Microsoft Learn

VS Code extension overview - Microsoft Fabric | Microsoft Learn

Synapse/Fabric Kernel is not available in VS Code. · Issue #13 · microsoft/SynapseVSCode

[TobiasKon]

Hi @v-hashadapu,

Thank you for your response.
I tried running the VS Code debugger while connected to a personal hotspot, and I now get a different error. The popup still shows:

Initializing Fabric Data Engineering PySpark debug session. This can take a few minutes.

But in the logs I see:

2025-09-01 09:18:17.181 [error] Error: command 'synapse-remote.internal.extensionIsReady' not found
at kKe.n (vscode-file://vscode-app/c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:1251:3892)
at kKe.executeCommand (vscode-file://vscode-app/c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/workbench.desktop.main.js:1251:3824)
2025-09-01 09:18:34.742 [error] TypeError: Cannot read properties of undefined (reading 'split')
at Object.provideFileDecoration (c:\Users\tgk\.vscode\extensions\synapsevscode.synapse-1.15.0\dist\extension\extension.js:210581:41)
at file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:119:4588
at Array.map (<anonymous>)
at xy.$provideDecorations (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:119:4524)
at C4.S (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:119615)
at C4.Q (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:119395)
at C4.M (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:118446)
at C4.L (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:117589)
at Jh.value (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:116386)
at $.C (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2373)
at $.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2591)
at fo.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:9458)
at Jh.value (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:388:8361)
at $.C (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2373)
at $.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2591)
at fo.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:9458)
at MessagePortMain.<anonymous> (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:388:6653)
at MessagePortMain.emit (node:events:518:28)
at Object.MessagePortMain._internalPort.emit (node:electron/js2c/utility_init:2:2949)
2025-09-01 09:19:07.622 [error] ExtensionError: Error in extension synapsevscode.vscode-synapse-remote: FAILED to handle event
at Jh.value (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:196:100366)
at $.C (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2373)
at $.D (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2443)
at $.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2660)
at Jh.value (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:196:62698)
at $.C (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2373)
at $.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2591)
at Cy.acceptDocumentsAndEditorsDelta (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:120:11788)
at Cy.$acceptDocumentsAndEditorsDelta (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:120:10247)
at C4.S (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:119615)
at C4.Q (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:119395)
at C4.M (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:118484)
at C4.L (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:117589)
at Jh.value (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:116386)
at $.C (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2373)
at $.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2591)
at fo.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:9458)
at Jh.value (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:388:8361)
at $.C (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2373)
at $.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:27:2591)
at fo.fire (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:29:9458)
at MessagePortMain.<anonymous> (file:///c:/Users/tgk/AppData/Local/Programs/Microsoft%20VS%20Code/resources/app/out/vs/workbench/api/node/extensionHostProcess.js:388:6653)
at MessagePortMain.emit (node:events:518:28)
at Object.MessagePortMain._internalPort.emit (node:electron/js2c/utility_init:2:2949)

I am not able to choose the synapse-spark-kernel kernel, I only have the option to choose Microsoft Runtime Kernel into the Pyspark kernel. 

So even outside my company firewall, debugging still fails with these extension errors.
Do you have any leads on what might be causing this?

[v-hashadapu]

Hi @TobiasKon , Thank you for reaching out to the Microsoft Community Forum.

Debugging Fabric notebooks won’t work in the VS Code web experience yet, only the desktop Fabric Data Engineering extension supports it. The error you’re seeing almost always means your company firewall or proxy is blocking the WebSocket connection that debugging relies on. Fabric needs both HTTPS and WSS access to *.pbidedicated.windows.net without TLS inspection. If it works on a personal hotspot network but not on your work machine, that confirms it’s the firewall.

Use desktop VS Code, select the synapse-spark-kernel and have IT allowlist or bypass SSL inspection for https://*.pbidedicated.windows.net and wss://*.pbidedicated.windows.net. Once that’s done, the debug session should start normally.