Last night I encountered this error message while building Ranting:

bash ActiveRecord::ConnectionNotEstablished (connection to server on socket "/tmp/.s.PGSQL.5432" failed: No such file or directory Is the server running locally and accepting connections on that socket? ):

I vaguely remember encountering this error message a while back 🤔. I’m not certain what actually caused the error, however I figured restatrting Postgress would solve this. Here’s how to do it.

1. Look for Postgres Installation

My current setup has Postgres installed with Homebrew.

bash $ brew list ==> Formulae ... cairo liblqr poppler coreutils libnghttp2 postgresql@14 docbook libomp protobuf ...

Seems that I have postgresql@14 installed.

2. Restart Postgres

Now, navigate to this folder:

bash $ cd /usr/local/var

Look for the same Postgres installation folder as in Homebrew list above.

bash $ ls cache homebrew mysql run db log postgresql@14

cd into the Postgres folder and look for a file called postmaster.pid.

bash $ cd postgresql@14

```bash $ ls PG_VERSION pg_ident.conf pg_snapshots pg_wal base pg_logical pg_stat pg_xact global pg_multixact pg_stat_tmp postgresql.auto.conf pg_commit_ts pg_notify pg_subtrans postgresql.conf pg_dynshmem pg_replslot pg_tblspc postmaster.opts pg_hba.conf pg_serial pg_twophase postmaster.pid

```

Found it! Next, backup the postmaster.pid file to another folder (eg. the Desktop folder) and restart Postgres.

bash $ mv postmaster.pid ~/Desktop

bash $ brew services restart postgresql@14 Stopping `postgresql@14`... (might take a while) ==> Successfully stopped `postgresql@14` (label: homebrew.mxcl.postgresql@14) ==> Successfully started `postgresql@14` (label: homebrew.mxcl.postgresql@14)

3. Move On with Life

Run Rails server again and that should resolve the error.

It should be safe now to delete the postmaster.pid that was backed up earlier.