SharePoint 2010 Error TaxonomyPicker.ascx

I love having a Development Environment I can simply return to a known snapshotted point, but it seems so long between new set ups that you forget some of the gotcha’s that you fixed when you initially set it up. This is one of those really frustrating ones that seems to appear on a lot of servers in the wild and one I’d completely forgotten about until today when I had to fix it again.

I got the following critical error :-

Web Controls Critical 7043 Load control template file /_controltemplates/TaxonomyPicker.ascx failed: Could not load type ‘Microsoft.SharePoint.Portal.WebControls.TaxonomyPicker’ from assembly ‘Microsoft.SharePoint.Portal, Version=, Culture=neutral, PublicKeyToken=71e9bce111e9429c’.

The fix for this is simple, open the TaxonomyPicker.ascx control which is in the hive under ControlTemplates (the full path is usually C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\CONTROLTEMPLATES) and take a look at the top of this file:-

<%@ Control className="TaxonomyPickerControl" Language="C#" Inherits="Microsoft.SharePoint.Portal.WebControls.TaxonomyPicker,Microsoft.SharePoint.Portal, Version=, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>

Highlighted in this snippet is the , which is the html encoding for a comma (,), by adding an actual comma and a space after it this issue is fixed, so this line should look as below:-

<%@ Control className="TaxonomyPickerControl" Language="C#" Inherits="Microsoft.SharePoint.Portal.WebControls.TaxonomyPicker, Microsoft.SharePoint.Portal, Version=, Culture=neutral, PublicKeyToken=71e9bce111e9429c" %>

Thats it fixed, the error is gone, if only all critical errors that appeared were that easy to fix.