SQL 2005 patch fails with 1642 “Unable to install Windows Installer MSP file”

This one is for all my DBA friends out there. I recently ran into this issue when running a security patch installation for a SQL 2005 instance on SP4. The setup failed, and when I looked into the “C:Program FilesMicrosoft SQL Server90Setup BootstrapLogHotfix” folder (this is where the patch setup files for 2005 are to…

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