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

19
votes

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.

2
xcodearchivepch
Thanks for contributing, one thing that you may want to do is rephrase or your original post as a question then post the solution as an answer (You wont be able to accept your own answer for a couple of days). This way some one looking for an answer for this issue will be able to find it and see that there is an accepted answer right away. meta.stackexchange.com/questions/17463/… – Joe
This would be the "option" key. (Some 3rd party keyboards don't label the option key as "ALT"). – Robert Altman

2 Answers

12
votes

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.

0
votes

I was experiencing another problem where this solution helped. After updating an external library I rely on, I got this message:

fatal error: file '/path/to/SomeHeaderFile.h' has been modified since the precompiled header was built

Using a "normal" clean already helped getting rid of it for Debug builds. But when I wanted to use Archive in order to create a new build for the AppStore, the error message remained.

Using that "Clean Build Folder" now finally solved the problem for me!