Error: Unknown Error Code 500 and Unexpected Application Error!

When I navigate to my streamlit page which lists my apps, sometimes the page is live for 30 seconds to a minute, but then it shows this error message:

This isn’t supposed to happen.
Please contact support.

Error: Unknown error
Code: 500

Other times it goes straight to that error, and even other times I will get an error like this:

Unexpected Application Error!
Loading CSS chunk 85 failed. (
Error: Loading CSS chunk 85 failed.
    at i.onerror.i.onload (

While trying to open my app, it just loads indefinitely, even after rebooting it and refreshing the page. It was working four days ago when I used it last, and I haven’t made any changes to the underlying code at all. Aaaaand I had the streamlit status page open in another tab, and I just checked it and it went from everything operational to outage. Well now I know what the issue is!

same here
service came back and shut down again

I am facing a very similar symptom.

My app started to fail at downloading CSS and JS chunks.

In the dev console:

main.7e6f4f72.js:2 ChunkLoadError: Loading chunk 8477 failed.

On the page itself:

Network issue:
Cannot load Streamlit frontend code. This can happen when you update Streamlit while a Streamlit app is running. To fix this, simply reload this app by pressing F5, Ctrl+R, or Cmd+R. If the error persists, try force-clearing your browser’s cache as described [here (Wikipedia:Bypass your cache - Wikipedia)

My app is deployed in AWS EKS and it’s been working fine for a good while and the errors started recently without any code changes. Anyone with any ideas how to debug this?

The app has been broken now for over a day, so it’s unlikely to be some transient network issue. Also find it strange, that if I refresh the browser on the broken page, nothing is loaded (full of 404 errors in the DevConsole network tab), I have to go to the root of the app, and then I can navigate to the broken page, which then loads with the error message on it.

It’s also odd that there is no errors in the server logs at all.