Troubleshooting

Invalid session

You get websocket/socket.io connection errors in the browser dev tools along with something like the following on the server logs:

Invalid session nms2Du11Yi15GwE2AAAA (further occurrences of this error will be logged with level INFO)

You’re most likely running your Socket.io service with multiple workers. This can happen if you set the XLWINGS_ENVIRONMENT=dev but are running multiple gunicorn or uvicorn workers. You have to run the Socket.io service with exactly 1 worker, see deployment/docker-compose.prod.yaml for an example production setup.

Error installing add-ins

When installing the Office.js add-in, you get the following error in the taskbar of Excel: “Addin xlwings Server failed to download a required resource”.

Make sure to run your server via https, not via http by using TLS certificates. This also means that you will need to use a domain name, not the IP address directly.