This is a bug fix release for 2.3 version.
Bugs

A critical infinite looping bug when retrieve space list in search result page.
Don't allow send blank message to admin.
Backup broken when page context has ASCII control characters - this caused invalid XML output.
Load system default theme by wrong name.
Anonymous doesn't have activities from profile page.
Contribute pages should list the current version for anonymous user.
Restore not success if database has been rebuilt before. This caused system queries system space by constant value - fix.