Sometimes when you are deleting and recreating databases, instead of DATABASE_URL pointing to the correct database, you end up with DOKKU_POSTGRES_AQUA_URL.
The old way to fix this problem was this line of code in our startup.sh script:
if [ -n "$DOKKU_POSTGRES_AQUA_URL" ]; then
DATABASE_URL="$DOKKU_POSTGRES_AQUA_URL"
fi
But there’s a better way.
Just run this command:
dokku postgres:promote appname-db appname
This will ensure that the database you reference (e.g. appname-db) is the one that DATABASE_URL actually points to.