Jellyfin 12.0 arrives, dropping the 10 and reworking playlists, episodes and books

Jellyfin, the open-source media server, has released version 12.0 — an update that changes the project's version numbering, reworks how playlists and alternate versions are stored, and moves book and comic support out of a plugin and into the server itself. The announcement was published on 7 September by core team member Cody Robibero.

Why the number jumped from 10.11 to 12.0

The most visible change is in the name. The project is dropping the leading "10": what would have been 10.12.0 is simply 12.0, and the server reports 12.0.0. Jellyfin says feedback after 10.11.0 — a release that rewrote the library database but looked like a minor update — drove the change. Anyone parsing version strings in clients, monitoring checks, deployment scripts or container tags should look at this before upgrading.

Upgrade caveats

12.0 changes the database schema and rewrites data on first boot, so the team warns that a backup is the only way back: stop Jellyfin and take a full manual backup of the data and configuration directories first. Servers must run 10.10.7 or a 10.11.x release to upgrade; older installations should move to 10.10.7 first. Usernames are now case-insensitive, so accounts differing only by capitalisation will break the migration. A full library scan is required afterwards, and automatically grouped alternate versions are cleared until it runs. Third-party plugins must be removed before upgrading — builds for 10.11 will not load and need new builds from their authors, while official plugins are ready.

Performance, episodes and books

The release builds on the database rebuild in 10.11. Every item in a playlist and every collection entry is now its own row, so the database can count, page and edit without loading an entire list; large playlists and bulk deletions should behave far better, Jellyfin says. Continue Watching, Next Up, artist lookups and watched counts are reported as faster, and heavy database maintenance no longer runs during a library scan. Alternate versions, previously a movies-only feature, now work for episodes too. Books and comics move into the server: metadata is read from OPF and ComicInfo files, posters are generated for EPUBs and comic archives, page counts and chapter numbers are extracted, and the Bookshelf plugin is deprecated in favour of GoogleBooks, ComicVine and a new OpenLibrary provider.

Defaults, security and client changes

The layout shipped as experimental is now the default Modern layout on desktop and mobile, with the old one kept as Legacy; televisions keep the TV layout. The release includes security fixes covering file access outside the directories Jellyfin serves, re-running the setup wizard on a misconfigured server, unsafe plugin package names, parental controls and cross-site scripting in the web client. Transcoding moves to upstream FFmpeg 8.1, and the server now targets .NET 10, so plugins need to be retargeted and rebuilt.