Jellyfin Server 12.0 RC3 Arrives as a Critical Preview Update
The Jellyfin team has rolled out the third release candidate for the upcoming 12.0 server version, inviting testers to help squash bugs before the final launch. As always, they strongly recommend backing up your server before upgrading, especially given this pre-release status.
A Fresh Versioning Approach
Starting with this release, Jellyfin drops the redundant “10.” prefix from its version numbers, moving from a scheme like 10.11.x to simply 12.x. The change eliminates long-standing confusion about what constitutes a major release, as the project no longer foresees the hard API break once planned in its early days. For more details, check the RC1 release notes.
Performance Takes Center Stage
The driving force behind 12.0 is performance. While the 10.11.0 release introduced a major backend overhaul, it left rough edges. This release candidate aims to smooth those out, delivering snappier response times and a more refined experience. For a deep dive, see the draft release notes and the Web client changelog.
Before You Leap
Upgraders must already be on Jellyfin 10.10.7+ or 10.11.x (ideally 10.11.11); otherwise the migration will fail. On first launch, 12.x runs several upgrades that can take a few minutes—please be patient and don’t interrupt the process. You can track progress via the improved startup UI by visiting your server’s URL. Also, disable all external plugins and reinstall from the unstable plugin repository to avoid load failures.
Getting the RC
This preview is available through all usual channels but not via automatic updates. For non-Docker setups, grab the files manually from the repository under “Stable Preview” for your OS. Docker users can pull the 12.0-rc3 or preview tags.
What’s Been Fixed and Improved Since RC2
This release candidate packs dozens of targeted fixes and enhancements. Performance-wise, resume querying sees a significant boost, book collection browsing is much faster, and the activity log user query is more efficient. Several issues around metadata and identification have been squashed: parental rating lookups now correctly handle multi-rating and country-specific codes (including Swedish and Greek ratings), actor images display immediately, and external images for audiobooks are supported. Multi-version content handling has been refined, and the “Identify” feature no longer returns wrong images. TV shows now show production companies under Studios, trailers are properly sorted, and TVDB provider ID support extends to movies.
Streaming and transcoding received substantial attention. Bitrate reporting is more accurate, live stream state errors are prevented, and a race condition in concurrent subtitle conversion has been fixed. Subtitle encoding for local files is corrected, VobSub MKS profiles match by container, and FFmpeg logs on Windows won’t garble. Trickplay generation now normalizes invalid PTS from containers, and a hybrid software decode/CUDA tone mapping pipeline bug was resolved. Syncing and session management are more robust: lost WebSockets no longer create zombie SyncPlay groups, logout doesn’t throw on a missing session, and authenticated user entities stay in sync with login timestamps.
Security and stability have also been improved. Path traversal vulnerabilities in plugins were closed, further directory traversal protections added, and the startup wizard can’t be re-run unauthenticated on misconfiguration. Corrupt keyframe data rows are skipped during backups, and ghost entries from deleted library paths no longer linger. Additional fixes include proper max login attempts enforcement, allowing username capitalization changes, and filtering language codes only for relevant items. On the book side, series names are now editable in item metadata, page counts are extracted from archives and PDFs, and creator names in OPF data are normalized. The release also welcomes first-time contributors alongside ongoing infrastructure updates like dependency bumps and CI improvements.
For the complete technical list, refer to the full changelog.
