Synaptic error message when press "Apply" (Focal)

[Mélodie]

I like using Synaptic, as it allows for a combination of tasks, such as select several packages to be installed, select leftovers to be removed, select update… This is why I always install Synaptic on my computers.

I have noticed this bug for a while now, in previous editions of Ubuntu as well, but I just used a turn around : either close Synaptic and restart it, or just click to "Apply" a second time.

This is what I want to report now:

The steps:

For example, select some packages, change your mind, deselect them, select other packages.
This is the error message:

E: Impossible de corriger les problèmes, des paquets défectueux sont en mode « garder en l'état ».
E: Impossible de verrouiller le répertoire de téléchargement

(approximate translation,
E: Unable to correct problems, bad packets are in "keep as is" mode.
E: Unable to lock download directory)

But, if I wait for Synaptic to reload itself, then click again to Apply, the message does not appear anymore, and then it works.

Sometimes, I had not even deselected formerly selected packages for this to happen. However, the above turn around seems to work each time.

However, for other users this might be a message they get stuck on.

Could this be debugged further, and fixed? How to debug it further?

Thanks,
Mélodie

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.