Repairing permissions is considered the Mac equivalent of snake oil or waving a dead chicken. It’s usually the first thing suggested for fixing problems, although in most cases it does nothing. There are a few rare problems that it actually does fix, and I encountered one of them today.
One of our customers has been having trouble installing our software on a certain group of machines. For the last week or so we were completely stumped. When I finally got access to their machine today I discovered that /Library/Frameworks had the wrong permissions.
On all of my machines, the permissions are 0775 (drwxrwxr-x), and owned by root:admin. On these particular machines it was set to 0755 (drwxr-xr-x). During the installation, a system specific module gets downloaded from the server and installed in that directory. Because of the incorrect permissions, that was failing. It turns out that the VPN software they installed was setting the permissions incorrectly.