MSI Program Being Patched Is Not Installed - Error 1642 Created February 16, 2011 00:17 by Adam Ruth, Updated July 13, 2017 18:29 Description The installer is attempting to patch or update an application that is not installed. Recommended Fix Ensure that the required application is installed. Have more questions? Submit a request 2 Comments Date Votes 0 Ryan Thompson December 11, 2014 22:08 What if it is installed? 0 Shane Corellian December 11, 2014 22:20 If the specific product is installed then there is a problem with either the existing installation or with the patch file. If you try installing the patch manually you may get some additional information for troubleshooting. What has probably happened is the revision info in the MSI file is incorrect or a registry key (probably under HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products (or Installer\Features) is missing. Sometimes a product may look like it is installed but actually a slightly different product is. This can happen, for example, when you attempt to apply a multi-language patch to a specific language product. This happens often with Adobe Reader. Article is closed for comments.