Hello,
I do hope when accessing the forum is obvious enough that people can perform a search, especially when comes to something specific like
I will not enumerate all the results, but just some …
and the wiki https://wiki.manjaro.org/index.php/Pacman_troubleshooting#Errors_about_Keys
Partial updates are NOT supported!
How did you ended up trying to remove packages in an update process, and especially core packages ?
Please take a look at https://wiki.manjaro.org/index.php/System_Maintenance