Even when the Binary paths are correctly set in the Preferences, you can sometimes still get this error. To find the root-cause of this error, you can click on the validate button next to the path and it will show you the actual problem.

As you can see, the path is correct however the actual issue is displayed when the validate button is pressed.

In my case though, the pg_dump and pg_restore are actually present at the path however, I seem to be missing a library which is causing this (Getting this error when manually executing it).

Re-installing or installing a newer version fixed this for me.