When I ran
apt update(instead of clicking on “Reload” in Synaptic), it ended with three warnings about unreachable sources. One is for launchpad.net, which has PPAs for things like musicbrainz and mkusb, and one is for the TeamViewer PPA, which I don't necessarily need any more.
But the last one is for
When I used FTP to consult that tree up to the xenial-security level, the
Release.gpgentries were preceded by a question mark icon instead of the normal folder icon. So I wondered what that could mean and could it be the reason why this system refuses to fetch anything from anywhere?
Anyway, I had just done a Timeshift snapshot, so I proceeded to
apt upgrade, as recommended by many. (Quite a scary thing, seeing it replace 660 packages – a lot more than shown in mintupdate – and frustratingly long, because of the inclusion of useless things, such as over 41MB worth of mint-backgrounds-sylvia. )
Then I rebooted.
Still no quick filter in Synaptic, but otherwise it seems to have been fixed; I was able to install xrdp.
mintupdate is another matter. It was also fixed, insofar as I was now able to update palemoon to the latest version, but I see no difference from before in the list of upgradeable packages. In fact, even in Synaptic, it looks like nothing has changed. For example, both say that my current version of gnupg is 1.4.20-1ubuntu3.1 and that 1.4.20-1ubuntu3.3 is available, but the latter was listed during apt upgrade as successfully downloaded.
Maybe it’s just as well that nothing was really updated.*
However, for future reference: Is there something else to do after an apt upgrade, to apply the changes?
* Confirmation of this is that
apt updatenow ends with the mention that “656 packages could be updated”.