Vista app compatibility: What's the story?

As Microsoft rounds the final bend of the winding Windows Vista road, I’m surprised we’ve heard so little about application compatibility.

Sure, Jim Allchin, co-president of the Platforms and Services division, recently played up the need for Vista testers to push hard on making sure existing applications are backwards-compatible with Vista. But Allchin also admitted in an open letter to developers posted to the Web late last week that “some of the (Vista) system enhancements, such as User Access Control, changes to the networking stack, and the new graphics model, may require code changes on your part.”

Microsoft states publicly, in its Vista Application Compatibility Cookbook: “While Windows Vista is highly compatible with most of the applications written for Microsoft Windows XP, Microsoft Windows Server 2003, and their service packs, some amount of compatibility breaks are inevitable due to new innovations, security tightening, and increased reliability.” (The cookbook is Microsoft’s guide for folks building new Vista apps and retrofitting existing ones so they will work on Vista.)

However, the cookbook claims, “overall, Windows Vista compatibility is high.”

But how high is it?

Symantec has been railing publicly about Microsoft breaking compatibility with antivirus and other security software, as have certain other security vendors.

I’ve been asking other testers what is working and what isn’t. Their reports back are mixed. One tester told me about half of the apps he has tested don’t work. Another said “a bunch” don’t work. Sounds like it’s the usual suspects –- antivirus, VPN products – applications that rely on the new Internet Explorer 7.0 and/or have to accommodate User Account Control.

If there is a comprehensive list of applications that don’t run correctly on the latest Vista test builds, I have not found it. I have asked Microsoft for such a list for a couple of weeks now, to no avail.

Microsoft is promising to detail more on the Vista app compat front at its upcoming TechEd conference in Barcelona in mid-November. But is that soon enough?

As Microsoft historians may recall, Microsoft hit some serious roadblocks, in terms of application compatibility, with Windows XP Service Pack (SP) 2. Just over a week after it released XP SP2 in August of 2004, Microsoft published a Knowledge Base article in which it listed problem applications that “seemed to stop working” or worked incorrectly with SP2. On the list were a number of key Microsoft applications, including SQL Server 200 and Microsoft CRM 1.2, as well as some major third-party applications from Macromedia, Symantec and Veritas, among others.

After the outcry that followed Microsoft’s disclosure, I’d expect them to think different with Vista. Why not publish a list of applications with problems before the operating system goes live? Why not head off unpleasant surprises at the pass?

Vista testers: What does your app-compat list look like for Vista? As of Release Candidate 1, what’s working? What’s not?