Getting the 1500 Error Message

Problem

The following message is displayed during the installation:

"Error 1500. Another installation is in progress. You must complete that installation before continuing this one."

Cause

There can be two causes to this issue:

  • Multiple instances of MSIEXEC.EXE are running at the same time.

    -Or-

  • The registry key that indicates an installation is in progress was not properly removed by MSIEXEC.EXE.

Solution

To solve this issue, you can:

  1. Reboot the affected machine.

  2. Try the installation again.

    -Or-

  3. Download Msizap.exe from Microsoft.
  4. Run it to remove unwanted Windows Installer information.