SOLVED: Jellyfin Server login works only via remote proxy but media details page never works

[DavidM42]

I recently moved my Jellyfin installation on TrueNAS Scale from TrueCharts to TrueNas Apps and copied all the configuration. I am using a caddy2 remote proxy to access it via https externally.

Even before the move to TrueNAS Apps (which I hoped would fix it) clicking on episode lists of shows or details of movies started to fail suddenly. In the browser, I see errors like 

> itemDetails.21d720f417042985d57e.chunk.js:2 Uncaught TypeError: Cannot read properties of undefined (reading 'getItem')
and
> Uncaught (in promise) TypeError: Cannot read properties of undefined (reading 'appName')

while trying to open the details pages.

This is the behavior while routing through my caddy2 remote proxy from outside. If I try to open it directly internally via http://192.168.178.IP:8096 I only get the login page which shows an endless blue spinner and following browser console error
> Uncaught Error: Server not found: 97eda71247654f86b30c89f31b53d8c3

I've included my jellyfin log in verbose mode, but I sadly could not find any problems or errors in it that helped me
https://gist.github.com/DavidM42/2dde8c5...dc0a850672

Thanks in advance for any help

[TheDreadPirate]

Can you try rescanning your library and selecting "Search for missing metadata"?

[DavidM42]

Can you try rescanning your library and selecting "Search for missing metadata"?

Thank you for your reply.
I tried that now and sadly still get errors while trying to open the episode list of a show (see screenshot)

Also jellyfin log of today: https://gist.github.com/DavidM42/1429c71...37dcaec2dc        

[TheDreadPirate]

How are you running caddy? As a one-liner or with a caddy file? Can you share that?

Also, do you have any script blockers of a pihole setup on your network?

[DavidM42]

I am running it as a TrueNAS Scale App (so as k3s pod) and I think the helm chart should be as following: https://github.com/truenas/charts/tree/m...y/jellyfin

I do not have a script blocker like PiHole running atm. Am only running uBlock Origin in my Browsers but I have that disabled for that page

[TheDreadPirate]

For testing, can you try disabling uBlock entirely? That's the only factor that makes sense at this point.

Do you have this issue with non-browser clients? Android/iPhone? Android TV?

[DavidM42]

Yes I have problems in the Android App of Jellyfin too.
When I try to use the Android App right now I get the same behavior as in non previously authenticated browsers: Connect -> Login Page -> Enter Login credentials -> submit -> Endless Spinner

[TheDreadPirate]

Do you have a baseurl set in Dashboard > Networking?

[DavidM42]

I did not have it set.

After checking that and tinkering with the network settings, I decided to just give up and start with a clean install.
After 2 Weeks of Downtime and unsuccessful debugging with no clear lead, I decided the ancient configuration volume was just broken beyond repair. Should have decided this earlier since the new install with basically all my configuration re instated took less than 2 hours.
Thank you for your help nonetheless, you really do your best helping people on here.