For me this was after adding a .png file to an existing .scn assets folder, plus also a .wav file. I searched and searched for multiple reasons and found that Xcode, owing to increased security, doesn't like extensions on files, I deleted the files and the project rebuilt fine, I then used terminal to 'cd' into the files in question directly and removed their extensions using the 'xattr' command in Terminal To Remove All Extended Attributes On a Single File Use xattr with the -c flag to "clear" the attributes: xattr -c yourfile.txt To Remove All Extended Attributes On Many Files To recursively remove extended attributes on all files in a directory, combine the -c "clear" flag with the -r recursive flag: xattr -rc /path/to/directory this link is useful also for some other fixes and more detail... https://stackoverflow.com/questions/4833052/how-do-i-remove-the-extended-attributes-on-a-file-in-mac-os-x