after the ONTAP update from 9.7P5 to 9.7P11 on 19.02.2021, it happens with us on a Linux FTP server that Windows mounts can no longer be created or break again after a short time - then they can not be remounted. There are always different shares.
Volumes/shares are definitely present and could also be mapped under Windows. - Errors on the NetApp cluster are not present in the event log.
Before the ONTAP update everything worked fine.
The affected Linux-Server - a virtual machine - uses SLES 12 SP 5 (SUSE Linux Enterprise Server 12 (x86_64)).
Here's an example:
ftpserv1:~ # mount -t cifs -o vers=3.0,username=HERE_WAS_THE_USERNAME_WRITTEN,password=HERE_WAS_THE_PWD_WRITTEN //FSDXXXXX/Produktion/XFirm/XFirmV/Program_Data/FBXX-FBYY-Kontoauszuege/sic /ftptrans/StAYY/XFIRM-KONTOAUSZUEGE
mount error(2): No such file or directory
Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) and kernel log messages (dmesg)
[11472.498939] CIFS: Attempting to mount //FSDEXXXXX/Produktion/XFirm/XFirmV/Program_Data/FBXX-FBYY-Kontoauszuege/sic
It could be upgrade related bug, but it could also be external (different DC it started using, time/NTP disparity between the client/storage/DC etc...) you can of course open a case to help you troubleshooting and to confirm if there's a known issue.