Problem
If you install a package in Discover (the KDE package manager), and then try to remove it, the latter operation will fail with a “Package not found” error. The same problem occurs if you remove a package and then try to install it again.
Related Issues
Bugzilla report: #2015809
Workarounds
The workaround here is to close and reopen Discover after the first operation, and then the second operation will work as expected.