SUMMARY If a single package has a problem, the entire update is prevented. Slack (for example) has an untrusted key. This prevents Discover proceeding. There is no way to exclude the offending package from the update so Discover becomes entirely unusable until some other means is used to clear the problem. Cf Apper, which allows excluding any package from an update and thus would allow the full update to proceed. In fact, Apper is able to offer the user the opportunity to install the package anyway, something else Discover doesn't do. SOFTWARE/OS VERSIONS Linux/KDE Plasma: Fedora 34 Workstation (available in About System) KDE Plasma Version: not available anywhere (obvious, at least) KDE Frameworks Version: 5,82.0 Qt Version: 5.15.2
Are you running it with offline updates? What error do you get?
I run it to inform me of updates so that I can press the button to apply them when I want. The specific instance I mentioned (I don't now remember if there was another and it hasn't occurred again since then) reported the untrusted key (I think). Again going on memory, using dnf at the cli it reports the untrusted key and asks me if I want to proceed anyway. I don't remember how, or if, Apper notified me but it also let me install it anyway and continue with the rest of the updates.
Getting this issue again today as it appears Slack has another update. It isn't possible to copy (in order to paste) the "update issue" (ie error). The text is Bad GPG signature found /var/cache/PackageKit/34/metadata/slack-34-x86_64/packages/slack-4-18.0-0.1-fc21.x86_64.rpm could not be verified. /var/cache/PackageKit/34/metadata/slack-34-x86_64/packages/slack-4-18.0-0.1-fc21.x86_64.rpm: digest: SIGNATURE: NOT OK Why would it be looking at a signature from Fedora 21?
If you're using interactive updates, you can exclude Slack from the list of packages to update to work around this brokenness. If you're using interactive update, you can't, because the whole point of interactive updates is to batch everything together and update all at once. In that case, you would need to follow up with your distro or the packagers of this app, if you got it from a 3rd-party repo (which is never recommended, FWIW).