Troubleshooting

pyodide.ffi.JsException: NetworkError: A network error occurred.

Most likely, you’re running into a CORS issue, see Web API Requests

Error initializing application: undefined is not an object (evaluating 'editorInstance.setScrollPosition')

Your browser engine (“WebView”), which powers modern Excel add-ins like xlwings Lite, is too old.

  • For the best experience, use a perpetual version of Office no older than Office 2021 or an up-to-date version of Microsoft 365.

  • On macOS, Ventura is the oldest version that is supported as the OS alone determines the version of WKWebView.

  • On Windows, Office 2019 is supported under certain conditions.

In any case, you can always use xlwings Lite by going to https://office.com with a reasonably modern browser (this also works with the free online version of Excel).

Unexpected error: SSL is not supported

Add ssl explicitly to requirements.txt.

The cell shows #NAME? when using custom functions

Clear your Office cache:

  • Windows

    1. Go to File > Options > Trust Center > Trust Center Settings > Trusted Add-in Catalogs

    2. Activate the checkbox Next time Office starts, clear all previously-started web add-ins cache., then click OK.

    3. Restart Excel

    Alternatively:

    1. Close Excel

    2. Delete the following folder:

    %LOCALAPPDATA%\Microsoft\Office\16.0\Wef

  • macOS

    • Close Excel via Cmd+Q

    • Run the following commands in a Terminal:

    rm -rf ~/Library/Containers/com.microsoft.Excel/Data/Library/Caches/
rm -rf ~/Library/Containers/com.microsoft.Excel/Data/Library/Application
rm -rf ~/Library/Containers/com.microsoft.Office365ServiceV2/Data/Caches/com.microsoft.Office365ServiceV2/
rm -rf ~/Library/Containers/com.microsoft.Office365ServiceV2/Data/Library/Caches/com.microsoft.Office365ServiceV2/
rm -rf ~/Library/Containers/com.microsoft.Excel/Data/Library/Application\ Support/Microsoft/Office/16.0/Wef/

See also: https://learn.microsoft.com/en-us/office/dev/add-ins/testing/clear-cache