That is a very peculiar choice. Why not use RDS ?
This happens when the container is not gracefully shutdown, so PostgreSQL will have to perform a recovery process on next start up.
This usually happens very fast, but if your database is big (your case) and/or the disk is slow (really your case) this can be too slow and our rebuild script doesn’t know what to do.
A simple recovery method is starting the container again with ./launcher start app, letting it run happily for some time (let’s say 1h) and trying a rebuild later.