A non-existing app keeps crashing I've removed an app long ago, but when I unlock the phone a message appears which says: "the app" has stopped

I had changed its location from internal to external before I remove it.

Also I have another app which keep stopping, I changed it to external too.

I cannot rechange the apps which I changed their location after I've updated  android system

These two apps are not English

J7 prime 2017
Android 8.1.0
Sometimes, a corrupted cache can make the system behave unexpectedly.

So, try clearing the cache partition from the recovery mode on android. It solves most issues.