FATAL: password authentication failed for user "postgres" (postgresql 11 with pgAdmin 4)

Question

I recently installed Postgresql 11, during the installation, there's no step to put password and username for Postgres. Now in pgAdmin 4, I wanted to connect the database to server and it's asking me to input password, and I haven't put any in the first place. Any one knows what's going on. Thank you!

Answer 1

For Windows variant - I too experienced this nasty bug because of pgAdmin for my Windows x64 install of version 9.2. It left my production paralyzed.

In folder C:\Program Files\PostgreSQL\9.2\data or C:\Program Files (x86)\PostgreSQL\9.x\data, you'll find the pg_hba.conf text file.

Find the following lines:

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# IPv4 local connections:
host    all             all             127.0.0.1/32            md5
# IPv6 local connections:
host    all             all             ::1/128                 md5

and change METHOD md5 to "trust" like this:

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# IPv4 local connections:
host    all             all             127.0.0.1/32            trust
# IPv6 local connections:
host    all             all             ::1/128                 trust

From Windows>Run type "services.msc" and enter find the right PostgreSQL instance and restart it.

Your DB security is now blown wide open! Heed the warning to return it back to md5 after changing the user password expiry time to say year 2099 for all the relevant users.