Intermittent “Unable to display this Web Part” messages

Applies To: SharePoint 2010

I few months ago I customized a view in SharePoint designer to turn the due date red for any past due items in the list. The end users really liked this but an obnoxious problem started turning up. Seemingly randomly we would get:

Unable to display this Web Part. To troubleshoot the problem, open this Web page in a Microsoft SharePoint Foundation-compatible HTML editor such as Microsoft SharePoint Designer. If the problem persists, contact your Web server administrator.

Correlation ID: Some GUID

Taking a look through our logs didn’t reveal anything and often a refresh or two would solve the problem. So it wasn’t really stopping business but it was pretty annoying. Adjusting the logging settings we finally saw some messages corresponding to the provided Correlation ID and found the issue was Value did not fall into expected range often followed by Stack Overflow exceptions.

Unfortunately the above error message is so generic it was pretty difficult to find anyone else even having the same problem, let alone the solution. Finally I came across this thread on MSDN discussing the exact issue. Instructions for fixing the problem and the background of this issue can be found on this article on Englando’s Blog. The solution presented was to get a hotfix from Microsoft. Fortunately, that is no longer necessary and the fix is provided in the February 2012 Cumulative Update from Microsoft.

The problem was introduced in the June 2011 Cumulative Update when Microsoft reduced the timeout for XSLT transformation (used whenever you customize a view in SharePoint Designer) from 5 seconds to 1 second. This is a good idea for public facing farms to help mitigate Denial of Service attacks but pretty unnecessary for internal farms like the one I was working on.

The timeout causes modified XSLTListView Web Parts and XSLTDataView Web Parts to sometimes show the “Unable to display this Web Part” errors. This is especially true if you have several columns (more transformation) or are doing anything of even mild complexity. The issue was “fixed” in the August 2011 Cumulative Update but broken again in the December 2011 Cumulative Update.

To fix this issue we installed the February 2012 Cumulative Update on our farm (More about our experiences with this update to follow). Keep in mind, however, that the update does not change the XsltTransformTimeOut but merely provides you the ability to do so using PowerShell.

To check your current timeout settings, simply use the following PowerShell:

$myfarm = Get-SPFarm

If you’re experiencing the above problem, you probably got a 1 back from the above command indicating that the timeout is currently set to 1 second. To set it to a more reasonable value (we choose the original 5 seconds) just do this (assuming you set the $myfarm object using the above powershell):

$myfarm.XsltTransformTimeOut = 5

That’s it, things are happy again.