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[dxue]

I am posting another simple question about rollback. I am just curisous about the way that Windows Installer handles rollback on versioned files. Say, file1.dll is the key file of a installation component. When upgraded to a new version of file1.dll at the same install location, will Windows Installer be able to roll back to the originally installed file1.dll if the entire upgrade installation fails? In the install sequence table, RemoveExistingProduct is placed in between InstallExecute and InstallFinalize. So the new version is installed on the top of the old one, then the old one is supposed to be removed. What if the removal of the old version failed?

[Stefan Krueger]

Windows Installer keeps a backup of any file it overwrites for rollback purposes, until the install transaction is finished. At the end of the install all those backups are being deleted.
Note however that rollback may be disabled on a given machine.