Jellyfin server v12.0 RC1 release

[Venson]

🚀 We are pleased to announce the first release candidate preview release of Jellyfin 12.0! 🚀
This is a preview release, intended for those interested in testing 12.0 before it's final public release. We welcome testers to help find as many bugs as we can before the final release.
As always, please ensure you stop your Jellyfin server and take a full backup before upgrading!

A note about versioning

Starting with this release, we are dropping the preceeding 10. from our versioning. Thus, 10.11.x -> [10.]12.x = 12.x. The reason is simple: at this point in the project, we don't envision a hard break in the API like we planned way back in the early days, and this version scheme was causing a lot of confusion amongst users about what a "major" release was.
Thus, we are now on two digits:

• The first digit is the major release. Expect signifiant changes between major releases. Do not ever auto-update to a new major release without first checking the release notes, and always take a backup of your server data and config before a major release upgrade.
  
• The second digit is the minor release. These are primarily bug and security fix releases, and do not introduce significant feature or functionality changes. You can, usually, safely auto-update between minor releases and should not need a full backup, but it is prudent just in case. You should also ALWAYS strive to run the latest point release as security fixes are embargo'd for at most 2 weeks after the release.
  

What's new?
The main goal of this release has been performance. 
10.11.0 dropped a major backend rewrite, and while it was broadly functional, it had a lot of rough edges. This release seeks to polish out most of those rough edges and bring better performance to all users.
There are many other small fixes, improvements, changes, and translations. See our draft release notes here or below for the full list of pull requests.
Note: You must be on Jellyfin 10.11.x (ideally, 10.11.11) before upgrading! If you are not, the upgrade will fail. I have been informed that I was wrong here, and upgrades from 10.10.7 are also possible, same as 10.11.x!
Note: The initial load of Jellyfin 12.x will run a few migrations and will take several minutes. Please be patient and do not interrupt the process.
Note: If you install the RC, you should disable all plugins and reinstall using the unstable plugin repository, or plugins may fail to load and cause unintended side effects.

Installing

This preview release is distributed in all our traditional forms, though not automatically via our Apt repository or latest tag.

• For all non-Docker environments, you can find the files for manual download in our repository by selecting "Stable Preview" for your OS.
  
• For Docker, you can pull the 12.0-rc1 or preview tags.
  

For the full changelog, please see the GitHub releases:
https://github.com/jellyfin/jellyfin/rel.../v12.0-rc1
https://github.com/jellyfin/jellyfin-web.../v12.0-rc1

[matt1984]

So pleased to see v12 getting ever closer to release.
I notice here it says me must update to 10.11.x first but in the draft notes we can go directly from 10.10.7.
Is the 10.11.11 stepping stone requirement planned to only be needed during the RC phase?

[toytown]

I was keen to see the difference in speed between this and 10.10.7.  But as to not have any left overs from my old versions cause problems, i decided to start with a clean slate.  I'm having problems with the docker.  It's downloaded fine, when run it creates files in the /config directory and also the /transcode directory, but browsing to the jellyfin url all i get is the splash screen (jellyfin logo). 

I checked the logs for jellyfin but everything seems fine

Code:

[2026-06-22 14:32:57.852 +00:00] [INF] [6] Emby.Server.Implementations.ApplicationHost: Core startup complete
[2026-06-22 14:32:57.852 +00:00] [INF] [6] Main: Startup complete 0:00:05.6088838
[2026-06-22 14:32:59.383 +00:00] [INF] [10] Emby.Server.Implementations.ScheduledTasks.TaskManager: "Clean Transcode Directory" Completed after 0 minute(s) and 0 seconds
[2026-06-22 14:32:59.937 +00:00] [INF] [19] Emby.Server.Implementations.ScheduledTasks.TaskManager: "Update Plugins" Completed after 0 minute(s) and 0 seconds

Is it a requirement of the RC that you be upgrading from a previous version?

Edit - I tried upgrading a 10.10.7 backup and after it had finished updating (checked the logs) i got the same splashscreen issue. Here is the javascript log when browsing the url if its helpful at all.

Code:

Uncaught (in promise) Error: item or serverId cannot be null
    at t.value (main.jellyfin.bundle.js?26c5ccd04b464d709020:2:233830)
    at t.value (main.jellyfin.bundle.js?26c5ccd04b464d709020:2:234039)
    at t.<anonymous> (main.jellyfin.bundle.js?26c5ccd04b464d709020:2:239829)
    at main.jellyfin.bundle.js?26c5ccd04b464d709020:2:463461
    at Array.forEach (<anonymous>)
    at Object.trigger (main.jellyfin.bundle.js?26c5ccd04b464d709020:2:463438)
    at s.addApiClient (main.jellyfin.bundle.js?26c5ccd04b464d709020:2:228769)
    at t.value (main.jellyfin.bundle.js?26c5ccd04b464d709020:2:240457)
    at main.jellyfin.bundle.js?26c5ccd04b464d709020:2:209219
    at Generator.<anonymous> (main.jellyfin.bundle.js?26c5ccd04b464d709020:2:207276)

[theguymadmax]

I was keen to see the difference in speed between this and 10.10.7.  But as to not have any left overs from my old versions cause problems, i decided to start with a clean slate.  I'm having problems with the docker.  It's downloaded fine, when run it creates files in the /config directory and also the /transcode directory, but browsing to the jellyfin url all i get is the splash screen (jellyfin logo). 

I checked the logs for jellyfin but everything seems fine

Code:

[2026-06-22 14:32:57.852 +00:00] [INF] [6] Emby.Server.Implementations.ApplicationHost: Core startup complete
[2026-06-22 14:32:57.852 +00:00] [INF] [6] Main: Startup complete 0:00:05.6088838
[2026-06-22 14:32:59.383 +00:00] [INF] [10] Emby.Server.Implementations.ScheduledTasks.TaskManager: "Clean Transcode Directory" Completed after 0 minute(s) and 0 seconds
[2026-06-22 14:32:59.937 +00:00] [INF] [19] Emby.Server.Implementations.ScheduledTasks.TaskManager: "Update Plugins" Completed after 0 minute(s) and 0 seconds

Is it a requirement of the RC that you be upgrading from a previous version?

Edit - I tried upgrading a 10.10.7 backup and after it had finished updating (checked the logs) i got the same splashscreen issue. Here is the javascript log when browsing the url if its helpful at all.

Code:

Uncaught (in promise) Error: item or serverId cannot be null
    at t.value (main.jellyfin.bundle.js?26c5ccd04b464d709020:2:233830)
    at t.value (main.jellyfin.bundle.js?26c5ccd04b464d709020:2:234039)
    at t.<anonymous> (main.jellyfin.bundle.js?26c5ccd04b464d709020:2:239829)
    at main.jellyfin.bundle.js?26c5ccd04b464d709020:2:463461
    at Array.forEach (<anonymous>)
    at Object.trigger (main.jellyfin.bundle.js?26c5ccd04b464d709020:2:463438)
    at s.addApiClient (main.jellyfin.bundle.js?26c5ccd04b464d709020:2:228769)
    at t.value (main.jellyfin.bundle.js?26c5ccd04b464d709020:2:240457)
    at main.jellyfin.bundle.js?26c5ccd04b464d709020:2:209219
    at Generator.<anonymous> (main.jellyfin.bundle.js?26c5ccd04b464d709020:2:207276)

A last-minute bug was introduced in RC1 that prevents new installations from starting up.

Existing installations will continue to work if you have previously logged in through a web browser. If you're still able to log in via a web browser, do not clear your cache; otherwise, you won't be able to log back in.

A fix for this will be included in RC2: https://github.com/jellyfin/jellyfin-web/pull/8088

[toytown]

Thanks for the update, i can't login to the upgraded docker as its on a different port. So i'll wait till RC2.

[cifri]

Hello!

First of all, thank you for your work!

I thought I would try RC1, I copied the stable version data into a new docker, deleted plugins, version 12 starts, but only the logo loads, no login. The log does not write any errors.

[theguymadmax]

That sounds like the same error above. Here is the issue on GitHub for tracking: https://github.com/jellyfin/jellyfin-web/issues/8090

We are working on the fix and publishing a new release candidate.

[cifri]

That sounds like the same error above. Here is the issue on GitHub for tracking: https://github.com/jellyfin/jellyfin-web/issues/8090

We are working on the fix and publishing a new release candidate.

yep
"[Error] Unhandled Promise Rejection: Error: item or serverId cannot be null"

[Necromind]

What about build-in HTTPS support? Earlier roadmaps showed the plan to remove this feature.
Is it or will it removed as planed? I currently use this feature.

[Subdivide7853]

Is there a workaround for this if we have already cleared cache? Or are we just stuck waiting on another release?