The probable cause of this is that an error occurred at some point in relation to the source location being on a drive that was not mounted anymore - as said here.
In my case the cause was that the megasync client was starting before the mounting of the drive on which the Megasync dedicated folder is located. An error takes place after which the megasync client should resume syncing: for some reason it doesn't sometimes.
To avoid that error the client can be set to start with a delay (as said here):
bash -c "sleep 5 && megasync"
Also, we need to be sure that the drive where the synced folder is located must be mounted at startup. I use Disks (gnome-disks) for this purpose, as said here.
Note that what most probably happened is that the dedicated location is not selected to be synced anymore.
Checking that option fixes the problem for the moment.
The probable cause of this is that an error occurred at some point in relation to the source location being on a drive that was not mounted anymore - as said here.
In my case the cause was that the megasync client was starting before the mounting of the drive on which the Megasync dedicated folder is located. An error takes place after which the megasync client should resume syncing: for some reason it doesn't sometimes.
To avoid that error the client can be set to start with a delay (as said here):
Also, we need to be sure that the drive where the synced folder is located must be mounted at startup. I use Disks (gnome-disks) for this purpose, as said here.