I found this nasty error when i tried to crawl my User Profiles from the Search Service Application. The reason for this is because the the account you are using may not have access to the user profile service, not necessarily the web application like the error suggests. Here is my fix for it.
Go to the Central Administration.
Click Application Management
Click Manage Service Applications
Click User Profile Service (not the link) to highlight.
Add the account you are using to crawl the sps3://site
Add “Retrieve People Data for Search Crawlers” permission level.
Recrawl your user profile content..