When you install PostgreSQL on Windows 7, it always report the following error:

Problem running the post-install step. Installation may not complete correctly.

… when the installation progress bar reached the end.

After the install, you will still see that darned error message (or something like non-fatal error occured). Do not despair! (For Windows Power Users, we are just assigning Full Control permission to Postgres account on the new PostgreSQL install folder). For other users, read on if you don’t know how to do it.

Specified Solution:

Uninstall PostgreSQL

Run command: net user postgres /delete

Click: Control Panel -> User Accounts -> Configure advanced user profile properties -> delete all “Unknown User” instances that seem to be left from PostgreSQL installation.

Run command: net user postgres dbpass /add

Run: compmgmt.msc -> Click Local Users and Groups -> Users -> postgres ->Member of -> Add… -> Administrators -> OK

Run: runas /user:postgres cmd.exe -> cd \ -> postgresql-8.4.9-1-windows.exe -> installed successfully without errors. Checked data folder and confirmed files created successfully.

Run: compmgmt.msc -> Local Users and Groups -> Users -> postgres -> Member of -> Administrators -> Remove

Run: compmgmt.msc -> Local Users and Groups -> Users -> postgres -> Member of -> Add… -> Power Users -> OK

Installation completed successfully! Enjoy