404 error when going to author

Im having a problem getting a blog site reconfigured after a migration to a new design . when trying to access the author listed in a blog in produces a 404 error saying "404 Invalid author id provided."
no author was provided in the request and the author does match the article author as ther is only 1 author in this new site.

this occurs clicking on author in a a blog or in the list of bloggers