Patch (minor upgrade) creation issues with MSM (merge modules) - wix

Question

I am facing issues with patches (minor upgrade) installation (updates) with MSM (merge modules).
I am creating MSI (test.msi) with texst.wxs. And inside text.wxs referring to app.msm file (there is a folder app, which contains so many folders and files. And harvesting this folder and making app.msm file)
Below are steps for making app.msm file.
heat dir "app" -gg -sfrag -template:module -srd -ke -var var.source -out app.wxs
candle -dsource=app app.wxs
light app.wixobj
Below is snippet of test.wxs file
<Directory Id='TARGETDIR' Name='SourceDir'>
<Directory Id='ProgramFilesFolder' Name='PFiles'>
....
....
<Directory Id='Config' Name='Config'>
<Component Id='APP_CLIENT' Guid='*'>
<Component Id='Manual' Guid='*'>
<File Id='Manual' Name='Manual.pdf' DiskId='1' Source='Resources/Manual.pdf'
KeyPath='yes'>
<Shortcut Id="startmenuManual" Directory="ProgramMenuDir"
Name="Instruction Manual" Advertise="yes" />
</File>
</Component>
</Directory>
<Directory Id='exmp_REPO' Name='!(loc.Merge_FolderTitle)'>
<Merge Id="LocalRepository" Language="1033" SourceFile="app.msm" DiskId="1"/>
<Component Id='exmp_REPOSITORY' Guid='*'>
<CreateFolder/>
<RemoveFolder Id='exmp_REPO' On='uninstall' />
</Component>
</Directory>
....
<Feature Id='Complete' Display='expand' Level='1' ConfigurableDirectory='MYAPPPATH'>
<ComponentRef Id='Manual'/>
<ComponentRef Id='App_CLIENT'/>
<ComponentRef Id='exmp_REPOSITORY'/>
...
...
I am able to make major upgrade with my test.wxs by using app.msm (merge module). But not able to make patch with successful installation. Patch install (update) is reflecting in version change in the "Programs and Features" and showing in "View Installed updates". The manual changes also are reflecting with patch update. But whatever the changes in "app" (which are created app.msm and referred in test.wxs) folder are not reflecting.
I have used 2 approaches for making patch, which are mentioend in below urls
1) http://wixtoolset.org/documentation/manual/v3/patching/patch_building.html
2) http://wixtoolset.org/documentation/manual/v3/patching/wix_patching.html
Please help in this regards.

Answer 1

First, I would advise to find out, whether the built patch contains the correct files or not. If not, you have a build problem, that the msm is not updated. If yes, you have most likely a problem with the content of the msm which may be not consistent with it's predecessor (especially GUIDs, table primary keys, etc.).
You can find out and see the content of the patch without installing with tools like Orca and Insted which you can search and download.
Second, using merge modules is highly complicating things, especially for patches, and of limited usefulness, if they are your own and you use them only once. Msms are primarily made for situations, where you need the .msm at least for 2 different MSI packages. I have seen a handfull of problems using merge modules in patches with other tools, BTW. I have no special experience here with WiX+patches+MSMs, but, it's as I said.
Last, but not least, you will have to choose, if you really want to keep this complexity in the future. As I remember, there are other possibilities in WiX to modularize / encapsulate parts of your software.

Answer 2

You can check the versions of files in merge modules and MSI files by opening them with Orca and looking in the File table. Or open the MSI file with Orca and then Transform=>View patch to see changes.
It may be obvious, but a binary versioned file will be replaced by a file with a higher file version. I mention because there is a belief out there that somehow "new" files replace "old" files, and that's wrong. Versions matter.
Generally you need to install a patch with an msiexec command that specifies REINSTALL=ALL REINSTALLMODE=omus. Double-clicking an MSP file will not necessarily just work unless you've arranged for it to do this internally with a custom action that sets them when PATCH is set.
The patch will not work if you break component rules. A common mistake is to remove a component during a patch, and that will result in an "advertised" update that doesn't actually update anything. In a verbose log look for SELMGR entries and text about removal of components is not supported. Setting the MSIENFORCEUPGRADECOMPONENTRULES property to 1 will fail the patch if you've done this.
If a file has no version whether it's overwritten depends on the replacement rules here, and there's some difference if the file is hashed or not:
https://msdn.microsoft.com/en-us/library/aa370531(v=vs.85).aspx
Also: how do you know the patch isn't working? If you have no file versions then you can't know if a file has been replaced unless you look very carefully. You cannot trust the dates because Windows changes timestamps when a file is installed. You really need to build binary files with file versions because everything like patches, hotfixes, service packs etc will use them to replace binary files. Otherwise for data files use file hashing.

Answer 3

I see several potential problems here, maybe even in addition to the other answers:
when you heat up files for your merge modules -gg autogenerates new component guids. This will not work with patches, since it'll basically add a bunch of new components (new guids each time!!). Also, you'll remove components this way, which is something you shouldn't do and which cannot be done easily, unless you still include the original merge module. And then you'll end up with path problems.
The tutorial for wix patching uses wixpdb files for diffing the original and the updated installer. With wixpdb files, merge modules will not be patched, irrespective of whether files changed in them or not. You will need to do administrative installations and then diff on the msi itself. You'll still have problem #1.
your wxs snippet is bad. At least the xml element is never correctly closed. Your Feature also has a MergeRef somewhere?
Some tips:
you can view what your patches do with a program called Orca. Open the original msi, then just drag your msp patch file on top of it.
rather don't use merge modules, they complicate things. You can also use heat to generate a fragment which you then simply include into your wix project.
use the wix patching approach (Patch element, not the PatchCreation element). It's easier, but you have the same control
don't autogenerate guids if you plan to update those autogenerated components with a patch. It won't be a problem with major upgrades :)

Answer 4

Just one important issue of a number of potential reasons while files are not updated correctly: You write, in your .msm is a high number of unversioned files, like .xml, etc.
Important rule:
EVERY unversioned file which is changed on the PC AFTER the first MSI install not by the MSI engine itself (e.g. you edited a config.xml file or so), will be normally NEVER updated by MSI again, not by patch and not by Major Upgrade. (With normally I mean, you have to take special actions, like uninstalling or especially specifying those files as socalled companion files).