And another upgrade year that the MSI file kills the upgrade

Question

So everytime we do an update we need to read and dig to find the guru answer of how to resolve this painful update. Why is this happening and how can this be fixed on both MS or Adobe end so we can normally upgrade Lightroom?
So far the FixIt utility from MS works, at least for me, it is now cleared up and isntalled....but others have had issues, and why is this so common and still an issue?

Answer 1

Hi,
The main problem with MSI installations is as follows (from my experience and from a developer point of view) :
MSI installers add a lot of entries to a database located in the registry under the key named HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer . If you look at this registry tree, you'll see that it contains tenths of thousands of entries which amounts, depending on the system, to several megabytes of data. Very often, a good part of these data are useless and/or related to uninstalled products.
The problem is that once this database has been corrupted, this can cause trouble to other installers. Corruption can be caused by a faulty installer, a faulty de-installer that leaves a lot of useless and harmful data behind, and by some registry cleaning tools.
The big flaw with the MSI technology is that nobody seems to be able to reverse engineer the state of the database and check whether it is healthy. There is absolutely no cleaning tool for this subtree of the registry. Many years ago, a lot of developers (among them many development MVPs and I for one) have requested from Microsoft a cleaning tool that would eliminate irrelevant or wrong data from the MSI database. Obviously, nobody has ever been able to write such a tool. There's very few usable documentation to allow writing such a utility and this would obviously be a time consuming development. I'm only aware of one single (very thick) book about the MSI technology written by a german developer who tried to make things clear. Very nice job but this was not enough information to produce an "MSI Cleaner".
The only "tool" made available by Microsoft is Windows Installer Cleanup that can only wipe out the data for a single product. It doesn't check anything, it deletes every entry related to a given product (which is rarely what we actually need). There's another tool that is able to delete everything (but I can do that manually with a registry editor). That's all.
IMHO, this explains why a given MSI installer (and especially MSI updaters) will work fine on certain systems and will fail on another. It depends on which applications (and Windows updates) were "MSI installed" or "MSI uninstalled" and in which order. The use of a registry cleaning tool may also generate trouble.
So it is extremely difficult to diagnose an MSI installation problem. Any MSI problem is tightly related to the system configuration and to the installation/uninstallation history of that system.
MSI is an ambitious technology but it often fails because it is not traceable, not debuggable and because its database cannot be repaired. Just totally or partially deleted.