Fix bugs with the installer that caused server errors.
This version has been installed onto XF Liam (twice), the dev forum & a new install on another dev forum. No errors arose, so I'm happy this version does fix the errors...
You must disable the add-on before uploading new files if updating from 3.6.3 (or a failed previous update). The database fields changed, and so uploading files will cause it to try and use the not yet installed fields.
If your installed version is 3.6.4 or 3.6.5, then make sure the correct tables are in place after updating - the tables may not have installed (which should've stopped installation, but some systems don't).