Reuse of external drive fails after "standby"

[DebianUser_HH]

Hello dear Community,

I have one problem which I cannot really explain. It started a couple of weeks ago (in my old Debian 9) and goes on in Debian 10. Here is my situation: I have Thinkpad R61i with external HDD in the Ultra-Bay-adapter. This drive has several virtual machines, I start from time to time. So, my regular procedure was mount HDD with double click, start VM, do my job, shut down VM. Important to notice here - it worked perfectly even after standy-mode of the laptop.

Suddenly I noticed, that I cannot mount that drive anymore after a standby. So, first time after start it works. But then, when I put the laptop into standby then back to work, the external drive cannot be mounted anymore. It it was mounted before standby, the content of the drive disappears from "Nemo". If it was not mounted and I try to mount, nothing happens. And if I make double click again, I see an error message saying that this operation is already pending.

The only solution in this case is to shutdown the laptop, and then start it again. Yes, it should be completely switched off - restart only does not resolve an issue. Does anyone have an idea, where I should search for the reason? I tried to check "dmesg", but I found only one message saying "mount operation took longer than 120 sec". I did not change neither stand-by-scripts nor HDD drivers. As I say, it started just from nothing...

Perhaps as additional information: also I noticed, that after a standby I cannot open my KeePass2-file stored on the WebDAV-server. In the "normal" case after entering my credentials I have to enter file password. In the "after-standby"-case I enter my credentials - and nothing happens. Not sure how it is connected together, but is also quite strange.

Thanks in advance,
Andrey

[Head_on_a_Stick]

No idea about Nemo (sorry) but why don't you just mount the drive via /etc/fstab instead?

EDIT: it would be better if you posted actual error messages rather than vague descriptions. Check ~/.xsession-errors and the systemd journal.

[DebianUser_HH]

No idea about Nemo (sorry) but why don't you just mount the drive via /etc/fstab instead?

Because, as I said, the HDD is in the UltraBay-adapter. It means, it can be replaced by DVD-drive if necessary. Besides, it never disturbed me that I hat to mount the drive before starting my VMs.

EDIT: it would be better if you posted actual error messages rather than vague descriptions. Check ~/.xsession-errors and the systemd journal.

I thought, my description is quite precise, I could reproduce this behaviour several times.
I checked .xsession-errorrs - there are no messages about problems after standby. But /var/log/kern.log and /var/log/syslog have several error messages. I try to paste them here...