After backup: Destination is read-only?

ncooper987 wrote:
I will be curious as to what you find.

Have narrowed it down to 1 directory with several long files names. It contains 30 files and about 30% has file names over 128, but no longer then 133 characters. That is still way less than the 255 max length.

#ls | awk '{ print length, $0 }' | sort -rn | head -1
133 .....

Also a long portion of these filenames is the same. The difference only occurs after about 100 characters.
Tried removing the hidden or archive flags and even the ACL, but that doesn't make any difference. Changed hidden files starting with . to names without dot. Doesn't make any difference either. Also the length of the path is not relevant to the problem. I now put the dir contents in \\NAS-XX-XX-XX\readydrop\metadata\plugins\org.eclipse.debug.core\launches, so nothing special I would say. I also tried to reduce the problem down to one file, but here's where it gets really strange.

If I remove a couple of files, the backup suddenly succeeds. But it doesn't matter which files are removed, as long as the total number of characters of all the filenames stays below 2112.
So I decided to keep all the files but reduce the number of characters in some filenames, so the total drops below the 2112 threshold.
Just adding 1 character to reach this threshold is the trigger point for the error "Destination is read-only" to occur. So 2112 produces the error, for 2111 characters the backup works.

# ls -1 . | tr '\n' '\0' | xargs -0 -n 1 basename | wc -m
2112

vs.

# ls -1 . | tr '\n' '\0' | xargs -0 -n 1 basename | wc -m
2111

But still not closer to a solution. Any thoughts, anyone?