rsync stopped with io-error

backup local desktop disk to unraid btrfs formatted disk with rsync (unraid pro 6.11.5).

Rsync stopped with following error:

Quote

2023/05/19 06:28:55 [41376] rsync: connection unexpectedly closed (2605909 bytes received so far) [sender]
2023/05/19 06:28:55 [41376] rsync error: unexplained error (code 255) at io.c(226) [sender=3.1.3]

At the time of the crash, a DMS (Devonthink) is being backed up.

An analysis shows that there are various files on the (unraid) target disk in the corresponding directory with file size = zero.

What all these files additionally have in common is that the name contain the three special characters "\|\" (without the quotes).

Example name of a file stored on the btrfs-disk (anonymized):

Quote

2015 xxxxx\ \|\ Xxxxx\ \|\ Xxxxxxxxx\ \|\ Xx\ Xx\ 58\ \|\ Xxxxxxx,\ 01.09.15\ 10-00.eml

Could this be the reason that Unraid is sending an (io) error to rsync ?