I am using "Web Request" and author.dll to move a document from one location to the another on SharePoint 2010 and 2013, it is working for few users and the other get the 401 error.
And when i run the workflow i get "Error performing web request. The remote server returned an error: 401 unauthorized"
checked my permissions on the site collection, sub site, source library and destination library and i have Full Control
Have followed this article to build my workflow