Recently I came across interesting error “/_vti_bin/TaxonomyInternalService.json/ValidateTerms 500 (Internal Server Error)” while referencing managed metadata taxonomy field in the publishing page layouts. I have couple of managed metadata fields referencing managed metadata term store. While updating published pages, I was getting popup box with error message stating “There was an error processing the request”.

As you may have noticed, I have previously blogged an article – SharePoint March 2013 Public Update, Invalid FormDigest, Client.SVC ProcessQuery 403 Forbidden and it was dejavu for me. I remembered I had came across similar client side web service call issue on the March 2013 Update while editing published page articles. Based on previous experience, my first instinct was to look at the FormDigest and sure enough, that was the culprit.

Resolution => Upgrade to August 2013 CU => As I have done with the “Client.SVC ProcessQuery 403 Forbidden” issue, this issue seems to have been introduced into the product in the March 2013 CU for both SharePoint 2010 and SharePoint 2013. Upon upgrading my current environment to August 2013 CU, I was able to fix this issue.

Additional Resource – http://sharepoint-community.net/profiles/blogs/sharepoint-2010-publishing-page-error-there-was-an-error