This is a known issue with v8 that has been fixed with 2016.1.5935.
I’d highly recommend to update to at least 2016.1 if possible. From my experience v8->2016.1 wasn’t hard to do, the only breaking change I recall is change of installation path (so need to update paths in ControlCenter/Scheduler/API calls). Rest should be compatible.
Added bonus is it also adds other fixes (including a fix to some memory issues which is always nice).
If for some reasons you can’t upgrade, there are a couple workarounds. They’re not ideal, but at least it will allow you to save the file.
- When a xaml gets locked, open a different one from the same project. This usually makes the old handle to be released and you’ll now be able to save the file.
- Use SaveAs and manually replace files.
There’s one more (releasing the handle manually from memory via external tools), but I don’t recommend it as it’s not that reliable (sometimes saving silently fails afterwards, which is understandable as we’re tampering with memory manually at that point, so all bets are off).