About: http://webisa.webdatacommons.org/116974817

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	I have exactly the same error.Deleted all directories except templates and images and installed 1.5.21 changing to existing database afterwards.
http://www.w3.org/ns/prov#wasQuotedFrom	joomla.org