[Bug]: Applications seems to crash due to loss of connection to the CSS file

[vindevoy]

Component

UI (ui.*)

Severity

P0 - Critical (crash/unusable)

Shiny Version

1.5.0

Python Version

3.13.7

Minimal Reproducible Example

Any example goes, as long as you use a .css

Behavior

My application written in Shiny is deployed on a server. The code on this server serves multiple dashboards. Basically, I start the same application with different configuration files and they all run with uvicorn on a different port. Caddy is in front of it to do proxying.

The source code of the dashboards is located on a network file share. Basically it is for access rights that we put it in each department's data directories.

All works, however, from time to time the application "crashes" and shows a hideous screen. We only see the 2 svg files of our icons. The rest is gone. When I go into the developer tools of Edge or Chrome, I can see it seems it has lost the connection to the .css file.

There is no way to recover from this. We must stop the uvicorn project and then it works again. We can assume there is a temporary glitch to file server, but the uptime of that thing is 99.99-percentish.

Error Messages (if any)

Environment

Windows 10/11
Any browser (we use Edge and Chrome)

[gadenbuie]

Hi @vindevoy, it's naturally going to be quite difficult for someone to answer this question because your situation depends on quite a few rather unique circumstances.

The source code of the dashboards is located on a network file share.

This sentence in particular stood out to me as the most likely point of failure. If I were in your shoes, I'd spend my initial debugging time budget looking into this network file share to see if it's causing any issues (e.g. by seeing if the problem replicates if I remove that piece from the system). I'd also recommend looking into bug reports about using uvicorn with a network file share.

Beyond that, I think you'll either need to get much more specific about the technology in use for us to be able to help debug (we'd really need to be able to run a minimal example that reproduces the problem). That's likely to be quite time consuming to create. Or you can hope that someone else with a similar environment and setup has also encountered and solved a similar issue and sees this issue.

[vindevoy]

@gadenbuie

I totally agree with you. It will be very difficult.

I can open the repo with the base code. It's a project called "Shiny Board" and I am allowed to make it public. The individual pages are not open as they contain business data, but I may be able to make dummy pages.

I have checked with our Windows team: they see no glitches, no entries in the event log, that indicate loss of connection, unavailability of the file share. Neither can I at the moment "force" the error to happen. In a company of 5000 people I am not allowed to bring the file share down. As you may expect. The error happens at random moments, we don't see any correlation in the timings.

I also have no clue at the moment if I would be able to reproduce it on for example ShinyLive. I trust Linux more than Windows. And the whole setup would be indeed different, ..

So indeed, I would already be glad if somebody notices this and says: "yes, we had this too".