That doesn’t look like anything to do with Able (not sure why enabling Able would cause the UHT to choke like that). It looks like you have either A.) A Windows permissions issue (try moving your project out of your User directory and into some simple thing like C:\MyProjects or something like that ), or B.) Some zombie process is holding on to that SharedPCH file, you could try manually deleting it and see if it lets you.