XCode 4 Archiving Error: one or more PCH files were found, but they were invalid

Question

Documenting an odd XCode 4 Error here for future reference:

"one or more PCH files were found, but they were invalid"

Cleaning does not fix the issue, you need to clean the Build Folder by holding down ALT and selecting Product from the menu. The "Clean" entry will now have changed to "Clean Build Folder" which will wipe the bad PCH duplicates and compile without errors.

Answer 1

I had to read this a few times to get what was going on. The original poster answered his own question. To fix:

Clean the Build Folder by holding down ALT and selecting Product from the menu. The "Clean" entry will now have changed to "Clean Build Folder" which will wipe the bad PCH duplicates and compile without errors.