computer error vs happening

computer error and happening both are nouns.

Word	Noun	Adjective	Verb	Adverb
computer error	Yes	No	No	No
happening	Yes	No	No	No

As nouns, happening is a hypernym of computer error; that is, happening is a word with a broader meaning than computer error:

computer error: (computer science) the occurrence of an incorrect result produced by a computer
happening: an event that happens

Other hypernyms of computer error include natural event, occurrence, occurrent.

computer error (noun)	happening (noun)
(computer science) the occurrence of an incorrect result produced by a computer	an event that happens