Failed to read dir on one library


I’m using Seafile since version 3.1.7 and upgrading. I’m now at version 6.1.2 on Ubuntu/64 server.

One of my libraries fails to sync with “Server error” on client side.
In the logs I see the following, repeated every second :

[08/22/17 12:53:40] ../common/diff-simple.c(134): Failed to find dir bcf47025-03ef-4acd-b0da-3c7feb30a939:9b083d9741e0ab00cefe434ceb6c2f683442f0ff.
[08/22/17 12:53:40] http-server.c(1246): Failed to diff remote and master head for repo bcf47025.

I have tried running seaf-fsck which said :

./ --repair bcf47025-03ef-4acd-b0da-3c7feb30a939

Starting seaf-fsck, please wait ...

[08/22/17 12:54:03] fsck.c(586): Running fsck for repo bcf47025-03ef-4acd-b0da-3c7feb30a939.
[08/22/17 12:54:03] fsck.c(413): Checking file system integrity of repo DocumentsMelmax(bcf47025)...
[08/22/17 12:55:49] ../../common/fs-mgr.c(2906): [fs mgr] Failed to read dir bcf47025-03ef-4acd-b0da-3c7feb30a939:9b083d9741e0ab00cefe434ceb6c2f683442f0ff.
[08/22/17 12:55:49] fsck.c(650): Fsck finished for repo bcf47025.

The other libraries work fine.

I can browse the non-syncing library via http with no problem. What can I do ?

Thanks for your help.

Any idea of what I can look for ?