I am trying to migrate from v3 to v4. I have about 20 sites.
I tried ./migrate.sh --dry-run --all command and now the dry-run is stuck at Copying site contents proc/kcore.
Then I saw a similar topic at How long does the v3 to v4 migration dry run take?
To continue from I broke the terminal command by pressing control+c and somehow even during dry-run the migration script migrated everything but incorrectly and now all my sites are down.