I recently completed an upgrade of SharePoint 2010 to 2013 for a customer that was using Reporting Services integrated mode fairly heavily. After the initial upgrade however, I was getting the following error whenever I tried to access a page that contained a Reporting Services report viewer web part:
Web Part Error: A Web Part or Web Form Control on this Page cannot be displayed or imported. The type Microsoft.ReportingServices.SharePoint.UI.WebParts.ReportViewerWebPart,Microsoft.ReportingServices.SharePoint.UI.WebParts, Version=10.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91 could not be found or it is not registered as safe.
The version of Reporting Services on the originating SharePoint 2010 farm was from SQL Server 2008 R2 (version 10) and the version in the new farm was SQL Server 2012 SP1 (version 11). The message pretty clearly indicates that it was having trouble loading a version 10 instance of the web part assembly, so I opened up the web.config file for my application, and sure enough, while there was a safecontrols entry for version 11 of the assembly, there was none for version 10. There was a binding redirect for the assembly itself (redirecting from version 10 to 11), so this was pretty clearly a bug in the installation process (SQL server install team take note!).
This would only affect content brought forth from an older SSRS system which is what I had. One solution would be to re-add all of the web parts onto the relevant pages. That would explicitly use new assembly references, but would also take a great deal of time. Another would be to directly edit the web.config files of all of the farm applications. While not generally considered best practice, this would solve the problem, especially since it corrects an oversight.
Hunting around, I came across my friend Chris O’Connor’s blog post on this very topic. Chris had this exact issue, and a rather large farm with multiple applications to deal with, so he built some PowerShell script to add these entries back in. The complete script is in Chris’ post.
In any event, regardless of the method used, adding the safe controls entry into the web.config file(s) fixes this particular issue. On to the next problem…..