Windows Installer Error 1601

Issue

The update or upgrade you are trying to install is not able to access the Windows Installer Service. This error could occur if the Windows Installer Service is disabled or if the Windows Installer Service is not registered properly.

Solution

To check if the Windows Installer Service is running:

1. On Windows, click Start > Run.
2. In Open, type services.msc and click OK.
3. In the Services (Local) list, right-click Windows Installer and click Properties.
4. Inspect the Start Up Type box. If it is set to Disable:
   1. From the Start Up Type drop-down list, select Manual.
   2. In the Service Status section, click Start.

To re-register the Windows Installer Service:

1. On Windows, click Start > Run.
2. In Open, type msiexec.exe /unreg and click OK.
3. Click OK, if a confirmation message appears.
4. On Windows, click Start > Run
5. In Open, type msiexec.exe /regserver and click OK.
6. Click OK, if a confirmation message appears.

If the problem persists, download the latest version of the Windows Installer from the Microsoft Support Site (http://support.microsoft.com/kb/942288) and install it on your computer.