failed to attach to process ID <ID number>

Anyone has experienced this problem? Yesterday I still can run my app in simulator but now I cannot run my app since Xcode prints this error in console:

error: failed to attach to process ID <ID number>




I experienced the same problem, and after a while I found out that it was due to the fact that my XCode project included a Folder Reference to a folder named Resources.

It seems that XCode doesn't like that name.

Just removing the folder reference or renaming the folder solved the issue.