Exchange 2013 CU3 causes headaches for OWA on Windows XP

The release of Exchange 2013 CU3 might just be the call to action to replace old browsers. Some early deployments (mostly test so far) have reported severe performance problems with Internet Explorer 8 (IE8) and Firefox version 24 when running Outlook Web App (OWA), with the likely culprit being some JavaScript problems that cause memory leaks and poor performance. It might well be the case that the new multi-platform touch-capable OWA architecture introduced in Exchange 2013 is too much for IE8 to handle.

We’ve known that IE8 and the Exchange 2013 version of OWA don’t get on too well for some time now. Indeed, Microsoft’s official stance for Office 365 is that support for IE8 will end on April 8, 2014.  KB2871314 provides a clue why OWA might have a problem in CU3 saying that IE8 users will experience:

“slow performance when they perform common tasks such as the following:

The article goes on to say that the problem is caused by “JavaScript performance and memory usage issues in Internet Explorer 8”. Pretty clear – use IE8 and have a nice day.

Given that Exchange 2013 CU3 is essentially an on-premises version of the Exchange Online software running in Office 365 (albeit several weeks or so in development terms behind), it should come as no surprise that if Office 365 damns IE8 with weak or no praise that Exchange 2013 won’t be too happy for people to use IE8 either.

What is surprising is that Microsoft hasn’t been more emphatic in getting the message across to on-premises customers, perhaps because some sensitivity already exists in the upcoming termination of extended support for Windows XP in April 2014. IE8 is, of course, the last version of the browser supported to be supported by Windows XP. Unfortunately the option to upgrade IE doesn’t exist as Microsoft doesn’t support IE9 and later versions on Windows XP.

Microsoft’s client support matrix for on-premises Exchange 2013 clients says that IE8 provides “good” support for OWA. This means that “Most Outlook Web App features are supported”. The word “most” is the most important in that sentence, yet its meaning is not further qualified in terms of saying what features work and what do not. Accordingly, you have the opportunity to do your own testing to find out whether the IE8/OWA combination provides “good” support for your users.

If you really must use IE8 (perhaps because you’re in the middle of a Windows XP upgrade project), the alternative is to ignore the premium version of OWA and downgrade to the light version, which works pretty well on almost any browser, including my experience using OWA on a really old Linux-based Firefox browser on a hotel TV. However, the light version isn’t as functional or as pretty as its premium counterpart so that might not be a popular course of action.

IE8 is a known problem area for OWA in Exchange 2013. The addition of Firefox version 24 (FF24) to the “bad browser” list for Windows XP clients is surprising. Microsoft’s client support matrix lists “good” support being delivered by Firefox version 17 and above and the reports that I have is the Exchange 2013 CU2 was perfectly happy with FF24. Now I hear that sky-high memory usage and hangs can be induced with FF24 by using OWA to scroll down through a folder. Not quite the experience you’d like to have and I am surprised and puzzled how this problem crept through Microsoft’s automated test harness, especially at a time when they really wanted to ship a quality update for Exchange 2013.

Windows XP is limping slowly toward oblivion. Yes, it takes time to upgrade clients in corporate environments and it’s a costly undertaking too, so I fully understand why people are still running Windows XP. As an O/S, XP is so much better than Windows Vista and although Windows 7 is a fine O/S for the enterprise, the cost of rolling out a new client O/S together with all the apps (for Office 2003 also has to be replaced) is enough to make most CIOs cry. So they’ve left XP in place and have been happy up to now. But the rock is rapidly approaching the hard place and the fact that the latest versions of Microsoft’s applications do not work well with 4-year-old software that is on the runway to be replaced is understandable, if frustrating.

Unless and until Microsoft comes up with some OWA magic (realistically unlikely to happen to fix severe performance problems with an obsolete browser), if you’re in the position that you have to run Windows XP clients with IE8, you should not upgrade your Exchange 2013 servers with CU3. The best idea is to keep on running CU2 and stay tuned to news. This is a bad position to be in because of the new support policy whereby fixes for bugs are only provided in cumulative updates, but it might be enough to get you through until your Windows XP replacement project finishes. That is, if you have a Windows XP replacement project…

In closing, Microsoft published KB2911802 yesterday to advise customers that a new Managed Availability probe, monitor, and responder called PublicFolderLocalEWSLogon introduced in Exchange 2013 CU3 (presumably to check the ability to log on to public folders using Exchange Web Services) don't work and should be disabled. It's a surprising glitch to see in CU3 as you'd have expected that something like this should have been caught by Microsoft's automated test harness. Oh well, c'est la vie.

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