Error - Migrations in Graphql/Prefect -"Could not upgrade the database! Can’t locate revision identified by ‘x’"

Are you just getting started with Prefect? If so, it would be better if you start with Prefect 2.0:
https://discourse.prefect.io/t/should-i-start-with-prefect-2-0-orion-skipping-prefect-1-0/544