Comment 15 for bug 1858011

I have also received this AppStream message.

I found in the console log: 'Could not open the AppStream metadata pool "Some components have been ignored: Metadata files have errors: /var/cache/app-info/xmls/mkyral-plasma-unstable.xml.gz"'

This references a repo that I previously had added which was having issues and I was no longer using. I removed the repo completely and also deleted the file it complained about above and the AppStream message disappeared. This is probably not the only possible cause of the message but hopefully this is helpful in figuring out what's going wrong.

SOFTWARE/OS VERSIONS
KDE Plasma Version 5.15.5
KDE Frameworks Version 5.59.0
Qt Version: 5.12.4