Microsoft Orca: If you have Visual Studio installed, try searching for Orca-x86_en-us.msi - under Program Files (x86) - and install it. Then find Orca in the start menu.
- Current path:
C:Program Files (x86)Windows Kits10in10.0.17763.0x86
- Change version numbers as appropriate
About MSI Files
Roughly speaking MSI files are COM-structured storage files - essentially a file system within a file - with streams of different content, one of which is a stripped down SQL Server database (in the most generic of terms I believe). Provided the MSI files are readable, the content (of various formats and types) can be compared.
Tech Note: It is conceivable that an MSI which triggers a System.BadImageFormatException is just not runnable (msiexec.exe can't run it), but it may still be readable - and hence comparable (please add a comment to verify this if you experience it).
Streams: Some streams in the MSI are tables with string values. There may also be streams for embedded cab-archives used to store files to deploy, and tables with binary content only - such as the Binary table where compiled and uncompiled custom actions alike are stored along with other binary content the setup needs. And there is a special "summary stream" and a table with icons stored in their native, binary format, and the list goes on... For most of the tables we can compare the strings in each table pretty much like we compare text in a Word document (which also used to be OLE / COM files - though newer versions now use Open Office XML) and get a detailed report of differences. In order to do this, you obviously need a special-purpose tool for the job - one capable of finding its way though all the relevant streams. Some commercial and free tools for this are listed below.
Binary content: Before elaborating this, I should note that comparing content in the Binary Table, Cabs Table, Icon Table - or any other binary table, will generally allow you a binary compare only (particularly for compiled custom action dll and exe files). Script custom actions - in the binary table - can be compared as text, but compiled custom actions are binary compare only. So if your problem emanates from a compiled custom action, you can't really see it in a direct compare (you see the binary difference only). You need to hit your source control system to see what code was used for compiled custom actions of any kind - hopefully you have a good label practice so you can find the actual source code used in each setup. I don't use this practice, but for internal, corporate releases perhaps you can even include your debug-build dll for your compiled custom action, and attempt to attach the debugger to the running code to really figure out what is going on? I wouldn't use a debug mode dll for a public release though - unless I'd clarified any risks. Debug code may be riddled with (unexpected) debug message boxes (used as entry points to attach the debugger) and other problems that should never hit a production package.
Come to think of it, your cab files and icon files can definitely be compared to their corresponding versions in older (or newer) MSI files by using the technique to decompile MSI files using dark.exe - which is described below. Then, using a good compare tool (Beyond Compare is mentioned below), you can do a full diff on the cab file content between different MSI versions (and some of the files could be text files, that could be text compared). I guess cabs and icons are sort of "transparent binaries" in an open format as opposed to compiled binaries (with custom actions and more) which are not inherently decompilable or inspectable (unless you know how to decompile managed binaries).
In conclusion: MSI files are fully transparent with the exception of compiled custom actions. This transparency is one of the core benefits of MSI. Most Windows Installer benefits, over previous deployment technologies, generally center around corporate deployment benefits. Unfortunately developers may only see the bad aspects of MSI: the (potential) MSI anti-patterns (towards bottom - very messy and ad-hoc for now). Admittedly some of these problems are very serious and violate "the principle of least astonishment". Developers - why have other and equally important things to do - may frankly be left scratching their heads in disbelief.
Leave no mistake about it though: MSI has massive corporate deployment benefits (see same link as above, towards bottom). Condensed: reliable silent running, remote management, rollback, logging, implicit uninstall feature, elevated rights, standardized command line, transparency, transforms for standardized setup customization and admin install to reliably extract files. Just to name the big ones quickly. Benefits in list form here.
A lot of digressions so far - let's get to the point. What tools can be used to compare MSI files?
Commercial Tools
Several commercial deployment tools such as Installshield, Advanced Installer and many other MSI tools have support for viewing and comparing MSI files. Maybe I add too many links, but let me use my usual policy of "if you link to one, you link to everyone" - it should save some time and some Google searches.
As a special note - a nostalgic one - the best MSI-diff feature I ever saw was in Wise Package Studio. It was head and shoulders above the rest to be honest - always working, neatly color coded and just easy to comprehend. This tool is no longer for sale as described here: What installation product to use? InstallShield, WiX, Wise, Advanced Installer, etc (if you have a packaging team in your corporation, maybe they have a spare license laying around?).
Free Tools
The commercial tools are good, but there are also several free alternatives that can be used to compare MSI files - and below is a list of some of them along with some hints for how to use each tool (in a rather minimalistic way).
There are some more details added for dark.exe - which is not a comparison tool for COM-structured storage files at all, but a way to decompile MSI files to WiX XML source files and extract all support files (icons, binaries, cabs, setup files) - allowing them to be compared with regular text / binary compare tools afterwards.
1. Orca (MSI SDK)
Microsoft's own MSI SDK tool / viewer called Orca can view MSI files and edit them, but there is no direct support for comparing two MSI files (that I know about). I suppose you could export the tables and then compare them, but other tools have more built-in features. This option is mentioned since you may already have Orca installed and then this is probably a quick way to get a simple diff done. The "poor man's option".
You may already have the installer. If you have Visual Studio installed, try searching for Orca-x86_en-us.msi - under Program Files (x86) - and install it. Then find Orca in the start menu. Technically Orca is installed as part of the Windows SDK (large, but free download). If you don't have Visual Studio installed, perhaps you know someone who does? Just have them search for this MSI and send you (it is a tiny half mb file) - should take them seconds. If not, you can always download the Windows SDK
2. Super Orca (free third party tool)
Super Orca will allow a rudimentary compare of two MSI files. My smoke test seems to reveal that advanced fields such as the Summary Stream may be ignored. In other words a straight table compare only. There could be other limitations. Maybe it is good enough? It is easy to use.
Note: I have not been able to verify for sure, but I believe this tool saved my MSI without warning once. That was very undesirable at the time.
The MSI SDK has a VBScript you can use to view differences between two MSI files. It is called widiffdb.vbs (msdn). With this tool I can see the Summary Stream differences ignored by Super Orca. Anything MSI SDK is authoritative.
UPDATE: All MSI SDK API scripts on github.com (the actual VBScript code).
- Throwing in a link to the full list of such MSI SDK VBScripts - for various purposes. Don't be confused, only
widiffdb.vbs is needed for comparing MSI files, but there are many useful scripts for other purposes to be found.
- If you have Visual Studio installed, just search for
widiffdb.vbs. Launch with cscript.exe</
