# Get error “Cannot set current directory to C:\blahblah” when trying to use SetDirectory command

I have used this exact same command in the exact same notebook literally hundreds of times and now for whatever reason it's no longer working and giving me this (rather unhelpful) error message. As far as I can tell nothing at all has changed on my computer and I'm certain nothing in the notebook has changed. Clearing the kernel does not help. I can't find any documentation.

• Last time I saw this message the drive had become unwritable. Is the volume off-line or in use? Can you access (and write to) that directory in other programs? – Mr.Wizard Jan 8 '17 at 17:39
• @Mr.Wizard Yes, I just checked and it's working fine :-( – quantum_loser Jan 8 '17 at 17:40
• Is it just this one directory? – Simon Woods Jan 8 '17 at 17:47
• Could Mathematica be running with different permissions than it usually does? Have you installed any other software recently? Any Windows updates? – Mr.Wizard Jan 8 '17 at 18:11
• It does look like a permissions problem, as @Mr.Wizard says. I don't have Windows, but as a first try I'd run something like this: Select[FileNames[All,FileNameJoin[{\$RootDirectory,"Users"}]],(FileType[#]==Directory)&] and see if it gives you this message for all directories in that list... – Jens Jan 8 '17 at 18:23