Full error:

mount error(115): Operation now in progress
Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)

This could happen if it tries to mount via dns name and it resolves to IPv6 e.g. example from fstab:

#//u111111.your-storagebox.de/backup /mnt/backup-storage cifs iocharset=utf8,rw,credentials=login.txt,file_mode=0660,dir_mode=0660 0 0

Try pinging the u111111.your-storagebox.de to get the ipv4 address (ping -4 u111…) and enter that in /etc/fstab/ (example if ping resolves to 11.22.33.44):

//11.22.33.44/backup /mnt/backup-storage cifs iocharset=utf8,rw,credentials=login.txt,file_mode=0660,dir_mode=0660 0 0

then try

mount -a

Another solution is to prefer ipv4 over ipv6 and the dns name should work again.

Error from journalctl -xe:

...kernel: CIFS: VFS: \\uxxxxxx.your-storagebox.de Send error in SessSetup = -13
...kernel: CIFS: Status code returned 0xc000006d STATUS_LOGON_FAILURE

When trying to ls the directory the error is:

ls: /mnt/backup-storage: Host is down

The above happened when using the Hetzner storage box. When using the IP address the mounting works. Another workaround is to leave the DNS name and lazy unmount and remount the cifs share e.g.

umount -l /mnt/backup-storage
mount -a

Try a couple of times above and then check with df -h and it should work again.

Example:

root@host:~# ls -l /mnt/
ls: cannot access '/mnt/backup-storage': Host is down
total 0
d????????? ? ? ? ?             ? backup-storage


root@host:~# findmnt
...
└─/mnt/backup-storage          //u287957.your-storagebox.de/backup
                                           cifs        rw,relatime,vers=3.1.1,cache=strict,username=xxxx,uid=0,noforceuid,gid=0,noforcegid,addr=159.69.63.181,file_mode=0660,dir_mode=0660,

It might be that the IP address changed and in /etc/fstab you have domain set up like so

//u287957.your-storagebox.de/backup /mnt/backup-storage cifs iocharset=utf8,rw,credentials=login.txt,file_mode=0660,dir_mode=0660 0 0

Try pinging the dns name:

~# ping -4 u287957.your-storagebox.de
~# ping u287957.your-storagebox.de

You should see that the IP changed. Now unmount and remount everything and it should fix it.

umount /mnt/backup-storage
umount //u287957.your-storagebox.de/backup

mount -a

• Use Hetzner storage box as docker volume

• https://serverfault.com/questions/414074/mount-cifs-host-is-down