MainMenu.nib permissions for installer only
Sage: Unable to read contents in the Interface Builder file at path /Applications/Sage-6.8.app/Contents/Resources/English.lproj/MainMenu.nib due to error: The file “MainMenu.nib” couldn’t be opened because you don’t have permission to view it..
bash-3.2# ls -ld /Applications/Sage-6.8.app/Contents/Resources/English.lproj
drwxr-xr-x@ 6 installer admin 204 Sep 22 13:22 /Applications/Sage-6.8.app/Contents/Resources/English.lproj
bash-3.2# ls -l /Applications/Sage-6.8.app/Contents/Resources/English.lproj
total 16
-rw-r--r--@ 1 installer admin 410 Jul 28 16:45 Credits.html
-rw-r--r--@ 1 installer admin 92 Jul 28 16:45 InfoPlist.strings
drwx------@ 4 installer admin 136 Feb 14 2014 MainMenu.nib
drwx------@ 4 installer admin 136 Feb 14 2014 MyDocument.nib
Also had the same problem with 6.5 10.10 app.
Can you give a few more pieces of information about exactly which file you downloaded, for which architecture, and what you are on? (e.g. If you are on 10.11 or something) This seems a bit suspicious but maybe the app was built with the wrong permissions.
10.10.5
.../sage/osx/intel/sage-6.8-x86_64-Darwin-OSX_10.10_x86_64-app.dmg
Changing the perms to: 755 /Applications/Sage-6.8.app/Contents/Resources/English.lproj/*nib
just results in "Read-only Sage" dialog box which implies that I'm running from the disk image instead of the hard drive.