Upgrade Failed from 2.7.0.beta1 to 2.7.0.beta3

I used the one-click browser upgrade to attempt to upgrade from 2.7.0.beta1 to 2.7.0.beta3.

It first updated docker, apparently successfully. Then, as instructed, I executed the following on the server:

    cd /var/discourse
    git pull
    ./launcher rebuild app

It completed and said I needed to rebuild again. So I did, and it got pretty far before displaying the following:

I, [2021-02-01T04:03:23.848858 #1]  INFO -- : > HOME=/var/lib/postgresql USER=postgres exec chpst -u postgres:postgres:ssl-cert -U postgres:postgres:ssl-cert /usr/lib/postgresql/13/bin/postmaster -D /etc/postgresql/13/main
I, [2021-02-01T04:03:23.850125 #1]  INFO -- : > sleep 5
I, [2021-02-01T04:03:28.854186 #1]  INFO -- :
I, [2021-02-01T04:03:28.854378 #1]  INFO -- : > su postgres -c 'createdb discourse' || true
createdb: error: could not connect to database template1: could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
I, [2021-02-01T04:03:28.940422 #1]  INFO -- :
I, [2021-02-01T04:03:28.940926 #1]  INFO -- : > su postgres -c 'psql discourse -c "create user discourse;"' || true
psql: error: could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
I, [2021-02-01T04:03:29.005802 #1]  INFO -- :
I, [2021-02-01T04:03:29.006192 #1]  INFO -- : > su postgres -c 'psql discourse -c "grant all privileges on database discourse to discourse;"' || true
psql: error: could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
I, [2021-02-01T04:03:29.055155 #1]  INFO -- :
I, [2021-02-01T04:03:29.055530 #1]  INFO -- : > su postgres -c 'psql discourse -c "alter schema public owner to discourse;"'
psql: error: could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
I, [2021-02-01T04:03:29.102737 #1]  INFO -- :
I, [2021-02-01T04:03:29.103136 #1]  INFO -- : Terminating async processes
I, [2021-02-01T04:03:29.103280 #1]  INFO -- : Sending INT to HOME=/var/lib/postgresql USER=postgres exec chpst -u postgres:postgres:ssl-cert -U postgres:postgres:ssl-cert /usr/lib/postgresql/13/bin/postmaster -D /etc/postgresql/13/main pid: 52


FAILED
--------------------
Pups::ExecError: su postgres -c 'psql discourse -c "alter schema public owner to discourse;"' failed with return #<Process::Status: pid 78 exit 2>
Location of failure: /pups/lib/pups/exec_command.rb:112:in `spawn'
exec failed with the params "su postgres -c 'psql $db_name -c \"alter schema public owner to $db_user;\"'"
74718f22e5eb9e1ceb21ac2a2fe613d13aee282a353cf60b91258ba2b2323397
** FAILED TO BOOTSTRAP ** please scroll up and look for earlier error messages, there may be more than one.
./discourse-doctor may help diagnose the problem.

The release notes warned about postgres and disk space; maybe it failed for that reason? When I run discourse-doctor, the output includes:

---------- OS Disk Space ----------
Filesystem                 Size  Used Avail Use% Mounted on
/dev/disk/by-label/DOROOT   30G   20G  8.5G  70% /

What should I do now?