Mastodon Updated to 4.6.6

We have updated C.IM to Mastodon v4.6.6.

C.IM was previously running Mastodon v4.6.4. Mastodon published v4.6.5 on August 6 and v4.6.6 on August 13, 2026, so both sets of fixes are included here. Neither upstream changelog lists a security advisory. Both releases focus on bugs in the Mastodon 4.6 series.

Collections and account data

Mastodon 4.6 introduced collections, and both patches clean up problems around them. v4.6.5 stops valid collection items from being rejected because the wrong attribute was read, and it applies the item limit consistently. v4.6.6 follows up by keeping the selected account in place while a collection is being created.

The v4.6.5 patch also corrects an account merge worker that mishandled Appeal and AccountWarning records. This is a backend correctness fix rather than a visible feature.

Web interface and administration fixes

Mastodon v4.6.6 fixes preview card creation when a connection error occurs while processing fediverse:creator metadata. It also restores access to the web interface for URLs ending in .zip.

For administrators, domain block impact queries are no longer rejected.

The full v4.6.6 changelog includes several smaller interface repairs around mobile navigation, video playback, alt text editing, and collection creation. We have kept this update focused on the changes with the clearest effect on browsing, federation, and administration.

Upgrade note

Both v4.6.5 and v4.6.6 require asset recompilation on non-Docker installations. Upstream lists no database migration or changed external dependency requirement for either patch.

Full changelogs:

C.IM source code: https://github.com/odotee/mastodon