Xcode fails without specifying and errors

Build operation failed without specifying any errors. Individual build tasks may have failed for unknown reasons. One possible cause is if there are too many (possibly zombie) processes; in this case, rebooting may fix the problem. Some individual build task failures (up to 12) may be listed below.

I've run into this problem consistently recently while running Xcode 9.0 Beta 3 and Xcode 8.3.3.

The fix is to delete ALL in the Derived Data folder. It then seems to work again.

rm -rf ~/Library/Developer/Xcode/DerivedData

NOTE: just cleaning the build or deleting the current build folder for a project does not seem to help.

Hope this helps :)

I was hitting this error and it infuriated me for an hour or so. The answer below helped me out a lot: essentially your machine has a ton of running processes, XCode can't handle it, and rebooting your machine is the best answer.

https://stackoverflow.com/a/13183522/1863655

I looked around for a bit and the only one that worked for me was shortening my project folder name.

All other tries: restarting, recloning, deleting derived data, etc. didn't work. The only thing that worked was making the project folder name shorter.