Yesterday I get this error message if I want to save an Publishing Page with an ContentType containing a Managed Metadatacolumn. After some googling I found some nice info’s from Ari Bakker.
The problem occurs because the Managed Metadata Column creates an additional field named MMdColumnName_0 from type Note. In the Metadata Column the Notecolumn is mapped through the TextField Property. If the TextField Property is empty or has the wrong guid the error occours. So if the error occurs please compare the guid with the ID from the Notecolumn via SPM2010 (The column is hidden) and corret the guid. If the Note column is not availible please add the Column to the list or the content type and correct the guid in the metadata column.