Created attachment 140234 [details]
Updates not Installing

file:///home/jannie/Pictures/Screenshot_2021-07-21_10-59-12.png

What does `pkmon` say (from a terminal window) while Discover is stuck?

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(In reply to Nate Graham from comment #2)
> What does `pkmon` say (from a terminal window) while Discover is stuck?

Since the OP doesn't respond, I'm taking over because of having the same problem, although on a different OS and KDE version.

I've found out, the problem gets away while switching back-ends from PackageKit-backend-zypp -> PackageKit-backend-dnf. This might indicate a bug in the Zypp back-end, however, with DNF, there are no respositories set in Discover settings except "lvfs - Linux Vendor Firmware Service" so DNF has got some mitigating circumstance. Moreover, If I disable all repositories while using the Zypp back-end, the problem goes away too.

I've also checked I'm not stuck while running "pkcon get-updates" so likely the problem is not within the Zypp backend but in Discover.

Created attachment 141261 [details]
pkmon.log

The whole pkmon output while launching "plasma-discover --mode Update", waiting a long time till it finished searching for updates, and then turning Discover off.

It's doubtful that the reporter had switched the backend to DNF the way you have, so your issue is a different thing. Can you please file a new bug report to track that separately in case more information gets added about this issue? Thanks!

I have the same problem since the update of my KDE Neon to the 5.25 anniversary version. When I try to update using Discover, it gets stuck on fetching updates, there is some process running in a loop, using 50% of the processor power (I couldn't track it though, in KSysGuard when I sort the processes by CPU usage, I see no individual process using more than 2-4%...). This stuck process does not stop when Discover is closed normally, but contiunes to use 50% of the CPU power. Killing Discover might or might not end it. Updates using pkcon work fine (I haven't tried updating through apt nor Synaptic, as they are not recommended for Neon).

Today I've installed the uptades through pkcon, rebooted the computer, launched pkmon, then launched the Discover, click on "updates", let it hang for 3 min, closed it, reopened it, clicked on updates again, then killed it. Here is what pkmon had to say:

Transactions:
 [none]
daemon connected=0
daemon connected=1
network status=online
Transactions:
 1      /10801_eecadbea
/10801_eecadbea allow_cancel 1
/10801_eecadbea percentage   -1
/10801_eecadbea role         get-updates
/10801_eecadbea status       setup
/10801_eecadbea status       loading-cache
/10801_eecadbea percentage   0
/10801_eecadbea percentage   100
/10801_eecadbea percentage   0
/10801_eecadbea percentage   50
/10801_eecadbea percentage   100
/10801_eecadbea status       query
/10801_eecadbea status       loading-cache
/10801_eecadbea percentage   0
/10801_eecadbea percentage   10
/10801_eecadbea percentage   100
/10801_eecadbea status       finished
/10801_eecadbea exit code: success
Transactions:
 [none]
Transactions:
 1      /10802_edebeedb
/10802_edebeedb allow_cancel 1
/10802_edebeedb percentage   -1
/10802_edebeedb role         get-updates
/10802_edebeedb status       setup
/10802_edebeedb status       loading-cache
/10802_edebeedb percentage   0
/10802_edebeedb percentage   100
/10802_edebeedb percentage   0
/10802_edebeedb percentage   50
/10802_edebeedb percentage   100
/10802_edebeedb status       query
/10802_edebeedb status       loading-cache
/10802_edebeedb percentage   0
/10802_edebeedb percentage   10
/10802_edebeedb percentage   100
/10802_edebeedb status       finished
/10802_edebeedb exit code: success
Transactions:
 [none]
Transactions:
 1      /10803_eaacacad
Transactions:
 1      /10803_eaacacad
 2      /10804_edacadaa
/10803_eaacacad allow_cancel 1
/10803_eaacacad percentage   -1
/10803_eaacacad role         resolve
/10803_eaacacad status       setup
/10804_edacadaa allow_cancel 1
/10804_edacadaa percentage   -1
/10804_edacadaa role         resolve
/10804_edacadaa status       wait
/10803_eaacacad status       loading-cache
/10803_eaacacad percentage   0
/10803_eaacacad percentage   100
/10803_eaacacad percentage   0
/10803_eaacacad percentage   50
/10803_eaacacad percentage   100
/10803_eaacacad status       query
/10803_eaacacad status       finished
/10803_eaacacad exit code: success
Transactions:
 1      /10804_edacadaa
/10804_edacadaa status       setup
/10804_edacadaa status       loading-cache
/10804_edacadaa percentage   0
/10804_edacadaa percentage   100
/10804_edacadaa percentage   0
/10804_edacadaa percentage   50
/10804_edacadaa percentage   100
/10804_edacadaa status       query
/10804_edacadaa status       finished
/10804_edacadaa exit code: success
Transactions:
 [none]
Transactions:
 1      /10805_edabcccb
/10805_edabcccb allow_cancel 1
/10805_edabcccb percentage   -1
/10805_edabcccb role         get-updates
/10805_edabcccb status       setup
/10805_edabcccb status       loading-cache
Transactions:
 1      /10805_edabcccb
 2      /10806_dbcbddca
Transactions:
 1      /10805_edabcccb
 2      /10806_dbcbddca
 3      /10807_babcdedb
/10806_dbcbddca allow_cancel 1
/10806_dbcbddca percentage   -1
/10806_dbcbddca role         resolve
/10806_dbcbddca status       wait
/10807_babcdedb allow_cancel 1
/10807_babcdedb percentage   -1
/10807_babcdedb role         resolve
/10807_babcdedb status       wait
/10805_edabcccb percentage   0
/10805_edabcccb percentage   100
/10805_edabcccb percentage   0
/10805_edabcccb percentage   50
/10805_edabcccb percentage   100
/10805_edabcccb status       query
/10805_edabcccb status       loading-cache
/10805_edabcccb percentage   0
/10805_edabcccb percentage   10
/10805_edabcccb percentage   100
/10805_edabcccb status       finished
/10805_edabcccb exit code: success
Transactions:
 1      /10806_dbcbddca
 2      /10807_babcdedb
/10806_dbcbddca status       setup
/10806_dbcbddca status       loading-cache
/10806_dbcbddca percentage   0
/10806_dbcbddca percentage   100
/10806_dbcbddca percentage   0
/10806_dbcbddca percentage   50
/10806_dbcbddca percentage   100
/10806_dbcbddca status       query
/10806_dbcbddca status       finished
/10806_dbcbddca exit code: success
Transactions:
 1      /10807_babcdedb
/10807_babcdedb status       setup
/10807_babcdedb status       loading-cache
/10807_babcdedb percentage   0
/10807_babcdedb percentage   100
/10807_babcdedb percentage   0
/10807_babcdedb percentage   50
/10807_babcdedb percentage   100
/10807_babcdedb status       query
/10807_babcdedb status       finished
/10807_babcdedb exit code: success
Transactions:
 [none]

I don't know if it helps, but when I launch Discover from the Konsole with the command "plasma-discover --backends packagekit-backend", it works fine, it does not hang on checking for updates.

And the content of my discoverrc file is:

[FlatpakSources]
Sources=flathub

[Software]
UseOfflineUpdates=false

[Window]
geometry=1019,130,858,709
visibility=2

Aha, this is Bug 443555.

*** This bug has been marked as a duplicate of bug 443555 ***