Hi,

PostgreSQL is not running; that's the only cause of this error. The Odoo installer bundles PostgreSQL, but leftover files/registry keys from the previous uninstall likely caused it to fail silently during reinstall.

Fix step by step:

1. Check if PostgreSQL service exists: Open services.msc and look for postgresql-x64-14 (or similar). If it's there but stopped, start it. If it's missing, PostgreSQL didn't install properly.

2. Clean reinstall of PostgreSQL: Since you already removed registry keys, also make sure these folders are fully deleted before reinstalling:

   C:\Program Files\PostgreSQL\
   C:\Users\<youruser>\AppData\Roaming\postgresql\
   

3. Reinstall Odoo 16; the installer will reinstall PostgreSQL bundled with it. Run as Administrator.

4. If the bundled PostgreSQL still fails, install it manually from https://www.postgresql.org/download/windows/ first, then install Odoo and point it to your existing PostgreSQL instance.

5. After installation, confirm PostgreSQL is running in services.msc before opening the browser.