I get the same error on Mac 10.9 - clicking more details shows a DF022: File corruption detected.
Hi jason412 and Brian Wood,
In order to minimize the patch size, we use incremental update mechanism, which requires all files to be updated keep intact. So if one or more files are corrupted, update will fail. Now you have to delete the Extension Manager CS6 installation folder, download Extension Manager 6.0.8 full installer from http://www.adobe.com/exchange/em_download/em6_download.html then install it.