Installation fails: ERROR: duplicate key value violates unique constraint

I just tried installing Events Booking in a fresh install of Joomla 3.8.13, using a PostgreSQL database. I got this warning:

ERROR: duplicate key value violates unique constraint "j_modules_pkey" DETAIL: Key (id)=(3) already exists.
Package Install: There was an error installing an extension: mod_eb_cart.zip

and this error:

Error installing package

After that, Event Booking does not appear in the Components menu. But under Extensions > Manage I do see an entry for "Events Booking - Cart Module". However, selecting it and attempting Uninstall or Refresh Cache results in an error message.

Hello Michael

The installation process is handled by Joomla core, so honestly, I don't know why the error happens

Maybe you can uninstall everything related to Events Booking, and then re-install it to see whether it solves the issue?

If the error still happens, send us super admin account of your site so that I can check and correct it for you

Regards,

Tuan