Problems instaling libpq-dev in ubuntu 20.04

Question

I am currently trying to install libpq-dev to install psycopg2. The problem is, when I try to install it, an error occurs saying I don't have the latest libpq5 version. However when I try to download the newer version of libpq5 the system says that I already have the latest version. An example of the error.

lhmendes@lhmendes-GA-78LMT-S2P:~$ sudo apt-get install libpq-dev
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 libpq-dev : Depends: libpq5 (= 12.4-0ubuntu0.20.04.1) but 12.4-1.pgdg20.04+1 is to be installed
E: Unable to correct problems, you have held broken packages.
lhmendes@lhmendes-GA-78LMT-S2P:~$ sudo apt-get install libpq5
Reading package lists... Done
Building dependency tree       
Reading state information... Done
libpq5 is already the newest version (12.4-1.pgdg20.04+1).
0 upgraded, 0 newly installed, 0 to remove and 4 not upgraded.

Answer 1

Any newer version of libpq5 can cause this error. In my case it was libpq5=13.1-1.pgdg20.04+1. It's the similar answer as furus has given but the change is it's libpq5 in ubuntu 20.04 (atleast in my case). I fixed the issue by installing

sudo apt-get install libpq5=12.5-0ubuntu0.20.04.1

and then install liqpq-dev again

sudo apt-get install libpq-dev

Answer 2

As of late October 2022 the command is:

sudo apt-get install libpq5=12.12-0ubuntu0.20.04.1 && sudo apt-get install libpq-dev