Totara Social 1.0.4.1 is an "emergency" release, being released ahead of schedule because it includes an important fix for an issue introduced in 1.0.4 that breaks the system upgrade during data migration.

A bit of background on this issue. This issue was introduced in the new tagging system, when the tags are migrated to the new way of storing data. In general, if upgrade does not run without issues, it rolls back and no data is lost. However, we advise that anyone who experienced problems during 1.0.4 upgrade roll back to the previous version and upgrade to 1.0.4.1. If you are still on a lower version you should bypass 1.0.4 and upgrade directly to 1.0.4.1 instead. If you have already upgraded to 1.0.4 without any issues, you don't need to upgrade to 1.0.4.1.

Here's the 1.0.4.1 Changelog:

Release 1.0.4.1 (5th March 2015):
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Improvements:
    TS-13124    Users will now automatically watch new blog posts of a watched blog
    TS-12716    Improved performance of activity_locate_typerecord() method in Activity Stream

Bug Fixes:
    TS-14132    Fixed upgrade issue when upgrading from Totara Social 1.0.3 to 1.0.4.
    TS-14115    "Confirm navigation" pop-up in tenant statistics is now suppressed