Unable to get list of updates

(Ubuntu budge)

Ubuntu budge running in Oracle vm in Windows 10.
I am connected to the internet.

When I try to update I get an error popup which says

"Unable to get list of updates.
E: Could not get lock /var/lib/dpkg/lock-frontend - open
(11: resource temporarily unavailable)

But it is not temporary. It keeps happening.
Searching on the internet I forced fsck on reboot by opening the terminal and issuing

shutdown -rF now

This rebooted Ubuntu, did a fdsk on restart and now updates seemed OK. But when I tried again to refresh updates the popup error reappeared.

What does “Could not get lock /var/lib/dpkg/lock-frontend - open” mean and how do I fix it?

Thanks.

Maybe another program is at the same moment making use of dpkg ?

If it happens in the minutes following your pc start, that may be your update manager automatically running in background ?

If it always happen then maybe the update manager in background is waiting for an answer that never comes ( network issue ) ?