Corrupted Windows Installer Service filesĢ. Some of the most common causes include:ġ. There are several reasons why you may encounter the “Windows Installer Service could not be accessed” error when trying to install an application. In this article, we will discuss some of the common causes of this error and possible solutions to fix it. Have you ever encountered the error message “Windows Installer Service could not be accessed” while trying to install an application on your Windows computer? This error can be quite frustrating as it prevents you from installing software on your system.