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If I have a 2.0 version of MyProduct installed through an MSI, is it possible to execute the MSI for an earlier 1.0 version of MyProduct and cause a "product downgrade?" Or does Windows Installer only handle upgrade stories?

Brent Arias
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Downgrades are supported. You can use the Upgrade table to define custom upgrade rules. For example, the 1.0 version should have an upgrade rule which covers all versions (including 2.0), not just versions lower than 1.0.

Cosmin
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  • I don't fully understand your answer. Are you saying that downgrades are supported by making "custom upgrades"? Are you also saying that a custom upgrade (for upgrades and downgrades) must be made for every target (1.0, 2.0, 3.0, 4.0, etc)? How is my 2.0 installer supposed to know about the existence of 3.0 and 4.0, if I have not made 3.0 and 4.0 yet? Or do I assume that I re-create my 2.0 installer to support an upgrade to 3.0 and 4.0 (when those become available)? – Brent Arias Feb 25 '11 at 18:16
  • Yes, downgrades are custom upgrades. For a downgrade row you can set VersionMin to ProductVersion and VersionMax to empty. Also, Attributes column should be 0 or 1025. – Cosmin Feb 28 '11 at 07:28