Recently I upgraded Configuration Manager 2012 to 2012 Sp1. We had a bunch of task sequences, but they wouldn’t open. I re-ran the configuration manager extension integration from the MDT 2012 Update 1 install, forcing the extensions down and resolved the error. I was thinking of blogging about this topic, and somone already did, 8 days ago. Nice work Jeroen Erkelens, here’s the Post.