Self-Repair, Simple & Short Explanation: Why does the MSI installer reconfigure if I delete a file?
Concrete Design Advice for your WiX / MSI File
I keep trying to write about repeating MSI self-repair for developers, but end up with too much detail. Here is my last attempt: concrete design advice for what not to do in your WiX / MSI file.
The answer below provides a checklist for solving any self-repair scenarios - from any vendor or source, not just your own. Check the answer linked above for your own MSI package design concerns.
The "Short Version" - Self-Repair Checklist
To permanently and reliably fix self-repair problems for everyone, developers and setup developers must be involved since the real fix must happen at the vendor level.
If you are in a corporate environment, poor-quality application re-packaging can also cause self-repair problems, and you should involve your application packagers to determine if the problem is from the vendor or not.
System administrators must know what they are looking at, and when no fix is available, use various workarounds to deal with the problem in the wild. Even end users can try some easy workarounds themselves (see section 5).
The essence of self-repair problems:
- Most self-repair issues are COM-related, and there are two general fixes for vendors and developers: 1) use the properly deployed, shared COM libraries generally deployed via merge modules, or 2) use registration-less COM to "shield" your application from self-repair and compatibility issues.
- Your setup developer can implement the merge module fix, developers must test. Merge modules are standardized, shared deployment libraries for shared files.
- Registration-less COM only works with developer involvement in my experience. This option is particularly relevant if the developer needs to use a particular version of a COM file (for whatever reason). Details in section 5.4 below.
- Apart from COM, you can also cause self-repair problems by having your setup developer register file- and MIME-associations and command verbs in your MSI setup. Use sparingly, and ensure your file-/MIME associations are unique.
- Finally you can cause self-repair by any file- or registry conflict between two installed MSI files. They "share a resource by mistake" and will treat it as its own - battling it out until the conflict is resolved.
- Some self-repair problems are not caused by errors in the vendor application or setup at all, but by external factors in the computer environment in question, such as interference from tinkering users, scripts, viruses, anti-viruses or security software. See section 3 for more details.
Quick Options For Dealing With Problem Applications
Perhaps jump straight to section 5 for the list of suggested fixes and workarounds if you are sure the self-repair you see is caused by MSI alone (and not by other, external causes as described in the first few sections below).
Most of these proposed "solutions" in section 5 are really mostly system administrator tricks that don't fix the underlying problem - as stated above the real fix has to come from the vendor. The exception is "5.4: registration-less COM", which can actually help developers "shield" their applications from self-repair problems.
If you don't have admin rights on your box you are advised to try "solutions" 5.2, 5.3 or 5.1 (5.1 will generally require admin rights to try, but it is non-complicated). These are "quick workarounds", the others are more involved. If these workarounds don't work, please ask your admin to read the other suggestions.
Understanding Windows Installer Self-Repair
I have written at length about this issue before, but it focused too much on understanding the problem rather than actually finding an acceptable fix for it. You can read the full explanation of self-repair problems here: How can I determine what causes repeated Windows Installer self-repair?.
Fixing Windows Installer Self-Repair Issues
To actually fix repeated and endless self-repair, you can try the suggestions below in section 5 - in increasing order of complexity and difficulty. Before doing so, you should verify what the real source of the self-repair problem really is. It might not be caused by MSI files, but by other, external causes (such as scripts or users deleting files or anti-virus blocking files).
If the problem is indeed MSI-related, you can try to disable advertised shortcuts and COM addins, use registration-less COM, get help from the application vendor, uninstall offending applications, virtualize packages or full on hack the cached MSI database and registry (not recommended, and only really possible with expert help). It all depends on your scenario. If external causes such as scripts are at fault, you must eliminate this interference. See details below - just follow the check-list.
The first steps for problem solving are to identify that the problem really exists in the wild on your platform, and then to determine what application(s) trigger the self-repair in the first place:
1. Verify that the problem really exists in your environment.
- It is generally always possible to figure out what is going on to cause the problematic self-repair, and there are several viable workarounds that can be utilized to deal with the problem. It is, however, not always possible to find a good, permanent fix (without vendor help - as described below).
- Accordingly, if you are a system administrator trying to find a fix for your self-repair issue, perhaps make sure the problem is seen on more than one computer - especially if the problem is seen on a developer-, QA- or even a test computer.
- If you only see self-repair problems on one computer, an alternative might be to rebuild the problem computer. Effectively eliminating rather than "solving" the problem. There is a relatively high risk that you might see the problem again though. If you ask me, don't rebuild, it is no solution - but what tends to be done in the real world I guess.
- Be aware that an AD-advertised MSI install that is slow to install and keeps getting aborted by users can "look like" a self-repair issue for desktop support, but this is expected MSI behavior. Allow the install to complete once (it is possible to change the installer progress bar to disable the cancel button - something like
msiexec.exe /I "MyApp.msi" /QB-! for progress bar only with no cancel button and no modal dialog at the end).
2. Identify the culprit(s) for the self-repair.
- It is possible for a single application to cause the problem on its own, but typically there are at least two applications that conflict (they share some resource by mistake).
- The trigger for the self-repair is generally possible to find in your event viewer on the system where the self-repair took place. Follow these steps to open the event viewer:
- Right click "My Computer"
- Click Manage
- Click continue if you get an UAC prompt
- Go to the Event Viewer section, and check the Windows Logs
- Identify the offending application in the Windows Event Log by looking in the "Application section" of the event log and you should find warnings from the event source "MsiInstaller" with IDs 1001 and 1004.
3. Verify that external non-MSI causes are not causing the problem
- Anything that deletes files or registry settings, manually or automatically, can trigger MSI self-repair. Especially if you are messing around deleting stuff in the user profile or in the HKCU section of the registry.
- In most cases such triggers will only cause a single self-repair to run and then the problem is fixed (this is how self-repair is supposed to work and help users). Allow self-repair to run once and then launch the application again to test if the problem is gone. It should be, and your application should launch correctly from now on.
- Special case: Ironically you can sometimes fix a broken application by renaming its HKCU application key (in the user section of the registry) to actually force self-repair to run and install the application's default data in the user profile - if that data was accidentally deleted (this type of fix generally does not work on terminal servers).
- If the same file or registry entry is deleted again by automated means and self-repair results, you must eliminate or update the automatic process that is causing it and your problem is solved and you can stop reading. If you manually deleted the file again yourself, then you may suffer from bad memory :-).
- In summary cleanup scripts, logon scripts, cleanup applications or tinkering, overactive users can all cause this kind of self-repair.
- Finally viruses and also a
