Jupyter in VSCode all of the sudden won't connect to my python kernels

[rsparks3]

This is wild and I have now wasted so much time on this, perhaps someone can help me.

I was running notebooks just fine last week, tried again on Friday and for some reason now nothing works. Here is the error message I am getting in the logs when I first start up VSCode. I have tried completely removing and reinstalling both the VSCode extensions, VSCode itself, and python. Can anyone point me in the right direction? I am pulling my hair out.

Visual Studio Code (1.99.3, undefined, desktop)
Jupyter Extension Version: 2025.3.0.
Python Extension Version: 2025.4.0.
Pylance Extension Version: 2025.4.1.
Platform: win32 (x64).
Home = c:\Users\ryan
Temp Storage folder ~\AppData\Roaming\Code\User\globalStorage\ms-toolsai.jupyter\version-2025.3.0
Workspace folder ~\Documents\hifld-to-pypsa
00:24:42.239 [warn] No interpreter with path ~\Anaconda3\envs\dsse\python.exe found in Python API, will convert Uri path to string as Id ~\Anaconda3\envs\dsse\python.exe
00:24:42.239 [warn] No interpreter with path ~\Anaconda3\envs\mg-sizing\python.exe found in Python API, will convert Uri path to string as Id ~\Anaconda3\envs\mg-sizing\python.exe
00:24:42.240 [warn] No interpreter with path ~\Anaconda3\envs\mapping\python.exe found in Python API, will convert Uri path to string as Id ~\Anaconda3\envs\mapping\python.exe
00:24:42.240 [warn] No interpreter with path ~\Anaconda3\envs\webscraping\python.exe found in Python API, will convert Uri path to string as Id ~\Anaconda3\envs\webscraping\python.exe
00:24:43.140 [error] Failed to validate Password info [D [FetchError]: request to http://localhost:8888/ failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)] {
  type: 'system',
  errno: 'ECONNREFUSED',
  code: 'ECONNREFUSED'
}
00:24:43.176 [error] Failed to validate Password info [D [FetchError]: request to http://localhost:8888/ failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)] {
  type: 'system',
  errno: 'ECONNREFUSED',
  code: 'ECONNREFUSED'
}
00:24:43.179 [error] Failed to validate Password info [D [FetchError]: request to http://localhost:8888/ failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)] {
  type: 'system',
  errno: 'ECONNREFUSED',
  code: 'ECONNREFUSED'
}
00:24:43.400 [error] Error fetching kernels from http://localhost:8888/ (localhost): [FetchError: request to http://localhost:8888/api/kernels?1746516283173 failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)]
00:24:43.402 [error] Error fetching kernels from http://localhost:8888/ (localhost): [FetchError: request to http://localhost:8888/api/kernels?1746516283174 failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)]
00:24:43.402 [error] Error fetching kernels from http://localhost:8888/ (localhost): [FetchError: request to http://localhost:8888/api/kernels?1746516283177 failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)]
00:24:43.550 [error] Error fetching kernels from http://localhost:8888/ (localhost): [FetchError: request to http://localhost:8888/api/kernels?1746516283181 failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)]
00:24:43.566 [error] Jupyter Lab Helper:getKernelSpecs failure:  [Error: Poll (@jupyterlab/services:KernelSpecManager#specs) is disposed.
	at i.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:35855)
	at Kr.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:75419)
	at c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\extension.node.js:181:18810
	at process.processTicksAndRejections (node:internal/process/task_queues:95:5)]
00:24:43.569 [error] Jupyter Lab Helper:getKernelSpecs failure:  [Error: Poll (@jupyterlab/services:KernelSpecManager#specs) is disposed.
	at i.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:35855)
	at Kr.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:75419)
	at c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\extension.node.js:181:18810
	at process.processTicksAndRejections (node:internal/process/task_queues:95:5)]
00:24:43.570 [error] Jupyter Lab Helper:getKernelSpecs failure:  [Error: Poll (@jupyterlab/services:KernelSpecManager#specs) is disposed.
	at i.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:35855)
	at Kr.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:75419)
	at c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\extension.node.js:181:18810
	at process.processTicksAndRejections (node:internal/process/task_queues:95:5)]
00:24:43.573 [error] Jupyter Lab Helper:getKernelSpecs failure:  [Error: Poll (@jupyterlab/services:KernelSpecManager#specs) is disposed.
	at i.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:35855)
	at Kr.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:75419)
	at c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\extension.node.js:181:18810
	at process.processTicksAndRejections (node:internal/process/task_queues:95:5)]
00:24:43.642 [error] Failed to validate Password info [D [FetchError]: request to http://localhost:8888/ failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)] {
  type: 'system',
  errno: 'ECONNREFUSED',
  code: 'ECONNREFUSED'
}
00:24:43.642 [error] Failed to validate Password info [D [FetchError]: request to http://localhost:8888/ failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)] {
  type: 'system',
  errno: 'ECONNREFUSED',
  code: 'ECONNREFUSED'
}
00:24:43.648 [error] Failed to validate Password info [D [FetchError]: request to http://localhost:8888/ failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)] {
  type: 'system',
  errno: 'ECONNREFUSED',
  code: 'ECONNREFUSED'
}
00:24:43.650 [error] Failed to validate Password info [D [FetchError]: request to http://localhost:8888/ failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)] {
  type: 'system',
  errno: 'ECONNREFUSED',
  code: 'ECONNREFUSED'
}
00:24:43.739 [info] Starting Kernel () for '~\Documents\hifld-to-pypsa\seoul\test.ipynb' (disableUI=true)
00:24:43.749 [error] Error fetching kernels from http://localhost:8888/ (localhost): [FetchError: request to http://localhost:8888/api/kernels?1746516283644 failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)]
00:24:43.750 [error] Error fetching kernels from http://localhost:8888/ (localhost): [FetchError: request to http://localhost:8888/api/kernels?1746516283646 failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)]
00:24:43.750 [error] Error fetching kernels from http://localhost:8888/ (localhost): [FetchError: request to http://localhost:8888/api/kernels?1746516283649 failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)]
00:24:43.757 [error] Error fetching kernels from http://localhost:8888/ (localhost): [FetchError: request to http://localhost:8888/api/kernels?1746516283651 failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)]
00:24:43.758 [error] Jupyter Lab Helper:getKernelSpecs failure:  [Error: Poll (@jupyterlab/services:KernelSpecManager#specs) is disposed.
	at i.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:35855)
	at Kr.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:75419)
	at c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\extension.node.js:181:18810
	at process.processTicksAndRejections (node:internal/process/task_queues:95:5)]
00:24:43.758 [warn] Could not fetch kernels from the remote server, falling back to cache: TypeError: request to http://localhost:8888/api/kernels?1746516283644 failed, reason: 
00:24:43.759 [error] Jupyter Lab Helper:getKernelSpecs failure:  [Error: Poll (@jupyterlab/services:KernelSpecManager#specs) is disposed.
	at i.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:35855)
	at Kr.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:75419)
	at c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\extension.node.js:181:18810
	at process.processTicksAndRejections (node:internal/process/task_queues:95:5)]
00:24:43.759 [error] UniversalRemoteKernelFinder: Failed to get kernels without cache [FetchError: request to http://localhost:8888/api/kernels?1746516283646 failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)]
00:24:43.760 [error] Jupyter Lab Helper:getKernelSpecs failure:  [Error: Poll (@jupyterlab/services:KernelSpecManager#specs) is disposed.
	at i.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:35855)
	at Kr.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:75419)
	at c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\extension.node.js:181:18810
	at process.processTicksAndRejections (node:internal/process/task_queues:95:5)]
00:24:43.761 [error] UniversalRemoteKernelFinder: Failed to get kernels without cache [FetchError: request to http://localhost:8888/api/kernels?1746516283649 failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)]
00:24:43.762 [error] Jupyter Lab Helper:getKernelSpecs failure:  [Error: Poll (@jupyterlab/services:KernelSpecManager#specs) is disposed.
	at i.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:35855)
	at Kr.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:75419)
	at c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\extension.node.js:181:18810
	at process.processTicksAndRejections (node:internal/process/task_queues:95:5)]
00:24:43.762 [error] UniversalRemoteKernelFinder: Failed to get kernels without cache [FetchError: request to http://localhost:8888/api/kernels?1746516283651 failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)]
00:24:43.776 [error] Failed to validate Password info [D [FetchError]: request to http://localhost:8888/ failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)] {
  type: 'system',
  errno: 'ECONNREFUSED',
  code: 'ECONNREFUSED'
}
00:24:43.807 [error] Failed to fetch running kernels from remote server, connection may be outdated or remote server may be unreachable [FetchError: request to http://localhost:8888/api/kernels?1746516283778 failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)]
00:24:43.808 [warn] Error occurred while trying to start the kernel, options.disableUI=true Error: Failed to connect to the remote Jupyter Server 'http://localhost:8888/'. Verify the server is running and reachable. (Failed to connect to the remote Jupyter Server 'http://localhost:8888/'. Verify the server is running and reachable. (request to http://localhost:8888/api/kernels?1746516283778 failed, reason: ).).
    > at ru.create (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\extension.node.js:282:2808)
    > url = http://localhost:8888/
    > serverProviderHandle = [object Object]
    > originalError = Error: Failed to connect to the remote Jupyter Server 'http://localhost:8888/'. Verify the server is running and reachable. (request to http://localhost:8888/api/kernels?1746516283778 failed, reason: ).
    > baseUrl = http://localhost:8888/
00:24:43.810 [error] Jupyter Lab Helper:getKernelSpecs failure:  [Error: Poll (@jupyterlab/services:KernelSpecManager#specs) is disposed.
	at i.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:35855)
	at Kr.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:75419)
	at c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\extension.node.js:181:18810
	at process.processTicksAndRejections (node:internal/process/task_queues:95:5)]
00:24:44.114 [warn] Disposing old controller connectToLiveRemoteKernel:'b171207d-2d66-4709-ac2c-ed525f0cbcc2' for view = 'jupyter-notebook'
00:24:44.117 [warn] Disposing old controller connectToLiveRemoteKernel:'b171207d-2d66-4709-ac2c-ed525f0cbcc2 (Interactive)' for view = 'interactive'
00:24:44.117 [warn] Disposing old controller connectToLiveRemoteKernel:'61318cbe-07ca-463c-b9a9-297739887a1a' for view = 'jupyter-notebook'
00:24:44.117 [warn] Disposing old controller connectToLiveRemoteKernel:'61318cbe-07ca-463c-b9a9-297739887a1a (Interactive)' for view = 'interactive'

Here are the errors I get when I try and run a notebook:

00:27:46.335 [info] Starting Kernel () for '~\Documents\hifld-to-pypsa\seoul\test.ipynb' (disableUI=false)
00:27:46.350 [error] Failed to validate Password info [D [FetchError]: request to http://localhost:8888/ failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)] {
  type: 'system',
  errno: 'ECONNREFUSED',
  code: 'ECONNREFUSED'
}
00:27:46.361 [error] Failed to fetch running kernels from remote server, connection may be outdated or remote server may be unreachable [FetchError: request to http://localhost:8888/api/kernels?1746516466352 failed, reason: 
	at ClientRequest.<anonymous> (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\node-fetch\index.js:1:306417)
	at ClientRequest.emit (node:events:518:28)
	at emitErrorEvent (node:_http_client:101:11)
	at Socket.socketErrorListener (node:_http_client:504:5)
	at Socket.emit (node:events:518:28)
	at emitErrorNT (node:internal/streams/destroy:169:8)
	at emitErrorCloseNT (node:internal/streams/destroy:128:3)
	at process.processTicksAndRejections (node:internal/process/task_queues:82:21)]
00:27:46.364 [error] Jupyter Lab Helper:getKernelSpecs failure:  [Error: Poll (@jupyterlab/services:KernelSpecManager#specs) is disposed.
	at i.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:35855)
	at Kr.dispose (c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\node_modules\@jupyterlab\services\index.js:11:75419)
	at c:\Users\~\.vscode\extensions\ms-toolsai.jupyter-2025.3.0-win32-x64\dist\extension.node.js:181:18810
	at process.processTicksAndRejections (node:internal/process/task_queues:95:5)]
00:27:51.430 [warn] Disposing old controller startUsingPythonInterpreter:'.jvsc74a57bd09920b9a7680cbc7a8562a6869bcc396ff71a1393ccd39dbe8c6df153b47296a1.c:\Users\~\Anaconda3\envs\py2\python.exe.c:\Users\~\Anaconda3\envs\py2\python.exe.-m#ipykernel_launcher' for view = 'jupyter-notebook'
00:27:51.430 [warn] Disposing old controller startUsingPythonInterpreter:'.jvsc74a57bd09920b9a7680cbc7a8562a6869bcc396ff71a1393ccd39dbe8c6df153b47296a1.c:\Users\~\Anaconda3\envs\py2\python.exe.c:\Users\~\Anaconda3\envs\py2\python.exe.-m#ipykernel_launcher (Interactive)' for view = 'interactive'

[rsparks3]

Update: as mysteriously as this issue appeared, it has now disappeared. Absolutely baffled. Thank you readers for your moral support.