Microsoft is running into more problems with its February update for its Windows Phone handsets.
Following the resumption of the update
earlier this week, the company is now looking into reports of an
unusual error code 800705B4 appearing during the upgrade process.
At the moment, there's no clear fix to this bug.
solves the problem for some (reboots, removing apps, freeing up space on
the handset) doesn't work for others.