BitmapCake!

I was setting up streaming replication between two Postgresql servers in active passive mode. After the setup was done, I tried to connect to the slave node to see if everything works fine and received the following error:

FATAL:  the database system is starting up

I was thinking for a while before I realized that I didn't set the slave node to hot_standby mode. It seems like a common mistake everyone does, so I thought of writing it down here hoping someone would find it useful.

If you get this error, this is what you have to do:

Open your postgresql.conf file.

vim /etc/postgresql/9.6/main/postgresql.conf
Locate the following

hot_standby = off
and change it as follows:

hot_standby = on

Save the file, then:

service postgresql restart

Now you can query your slave server ;)