'git annex add' no longer works for filenames of 127 characters or more.
I have longer names in my repository, so it must be a recent regression.
A workaround is to add with a shorter name and use 'git mv'.
$ touch AAAAAAAABBBBBBBBCCCCCCCCDDDDDDDDEEEEEEEEFFFFFFFFGGGGGGGGHHHHHHHHIIIIIIIIJJJJJJJJKKKKKKKKLLLLLLLLMMMMMMMMNNNNNNNNOOOOOOOOPPPPPPP
$ git annex add AAAAAAAABBBBBBBBCCCCCCCCDDDDDDDDEEEEEEEEFFFFFFFFGGGGGGGGHHHHHHHHIIIIIIIIJJJJJJJJKKKKKKKKLLLLLLLLMMMMMMMMNNNNNNNNOOOOOOOOPPPPPPP
add AAAAAAAABBBBBBBBCCCCCCCCDDDDDDDDEEEEEEEEFFFFFFFFGGGGGGGGHHHHHHHHIIIIIIIIJJJJJJJJKKKKKKKKLLLLLLLLMMMMMMMMNNNNNNNNOOOOOOOOPPPPPPP
git-annex: ../../../../.git/annex/objects/Jx/11/SHA1-s0--da39a3ee5e6b4b0d3255bfef95601890afd80709/SHA1-s0--da39a3ee5e6b4b0d3255bfef95601890afd80709: createSymbolicLink: invalid argument (File name too long)
failed
git-annex: add: 1 failed
$ touch AAAAAAAABBBBBBBBCCCCCCCCDDDDDDDDEEEEEEEEFFFFFFFFGGGGGGGGHHHHHHHHIIIIIIIIJJJJJJJJKKKKKKKKLLLLLLLLMMMMMMMMNNNNNNNNOOOOOOOOPPPPPP
$ git annex add AAAAAAAABBBBBBBBCCCCCCCCDDDDDDDDEEEEEEEEFFFFFFFFGGGGGGGGHHHHHHHHIIIIIIIIJJJJJJJJKKKKKKKKLLLLLLLLMMMMMMMMNNNNNNNNOOOOOOOOPPPPPP
$
- Michael