5: Input/output error Error: Failure while executing; `/bin/launchctl bootstrap gui/502 and FATAL: password authentication failed for user

This is what I did to resolve on my Mac.

1. Looked at the postgres.log cat /usr/local/var/log/postgres.log | tail -100
2. Found the following error on my logs FATAL: lock file "postmaster.pid" already exists
3. Fix above PID issue and restart the server.

rm /usr/local/var/postgres/postmaster.pid 
brew services restart postgresql