Why does a directory and pathname reader throw a write permission error?

I’d be interested to understand this too. I’ve noticed some other formats (SQLite being on of them) will often lock the entire database for just a read

I saw you open a support case regarding this issue and that this may have been related to changes with your network shares. I'm also sharing the idea you created here for visibility:
https://community.safe.com/ideas/directory-and-pathnames-reader-skip-invalid-paths-40791

Sounds like when scanning your network drive, the reader was hitting write-protected paths (along with hidden/system/invalid folders) and erroring out instead of just skipping past them, which meant working around it by pre-filtering folders you weren't interested in scanning in the first place.

I'd encourage other users running into this to upvote for a future inclusion in FME!