Deleting "pg_path =None" work fine for Me in /etc/odoo/odoo.conf

I found the answer in issues: https://github.com/Yenthe666/InstallScript/issues/178 and it worked for me

"I assume the script has copied over the configuration value pg_path = None in your config file. If it is set to None it will give a false positive resuling in this traceback. Can you check the configuration file, remove this option, restart the Odoo instance and try again? That should solve it."

open your odoo.conf and find pg_path inside of it

change your default pg_path for example:

pg_path = C:\Odoo\PostgreSQL\bin

to your current pg_path (in this case the path of your PostgreSQL bin)

for example:

pg_path = C:\Program Files\PostgreSQL\16\bin

save and restart odoo service, after that reload your page.

try to backup once more

Try to add the bath of PostgreSQL client in Odoo config file as below:

pg_path = /path/to/postgresql/bin  

Please refer to the below thread:

https://www.odoo.com/forum/help-1/question/command-pg-dump-not-found-87849