If your package contains only the application pool then you can try the following settings:
-- in the old package go to Table Editor page and locate InstallExecuteTable
-- here you will find the action "AI_IIsUninstall" with the condition "(VersionNT >= 500) AND (REMOVE="ALL")"
-- edit the condition field and set it to:
- Code: Select all
(VersionNT >= 500) AND (REMOVE="ALL") AND (NOT UPGRADINGPRODUCTCODE)
-- also, very important, in the new package, i.e. new version, in the "Error Policy" group of the application pool should be set to "Skip item installation"
This will make the package to not uninstall anything installed from the IIS page if an upgrade is in progress.
Please note that if you have an other web sites or virtual directories in the package these will not be removed either.
Let us know if you have any questions.