Why the TaxonomyPicker.ascx is no longer used
So some good SharePoint folks have stumbled into an error pertaining to the TaxonomyPicker control. (Links are at the bottom.)
My guess here is that the TaxonomyPicker.ascx control was left behind – obsolete. Nothing Taxonomy-related is found in Microsoft.SharePoint.Portal. For Taxonomy – or managed metadata – look to the Microsoft.SharePoint.Taxonomy.dll found in the 14\ISAPI folder.
The fact is, I don’t see any place in SharePoint where the control is being used. It has probably been replaced with the page TaxonomyTreePicker.aspx. It is used when you are filling in metadata for a field of type TaxonomyField (gui calls it “Managed Metadata”).
Here is this page in action:
If you look at the source (Right click and View Source on the form), you’ll see the traces pointing back to the TaxonomyTreePicker.aspx file.
So why does the error matter? Well, when you run an IISRESET or reboot, IIS will try to load the usercontrols into memory. I don’t like manually editing files, especially usercontrols. So I’m going to leave it alone.