LinkedIn login was working fine until a few days back and in the recent past, it has been giving an error message as "The redirect_uri does not match the registered value" for LinkedIn.
When we debugged the source, we observed that the function auth() from controller.php is returning the error message as given above when the url given below is triggered.We believe that the error is at the first level authentication from your api.slogin.info.
www.linkedin.com/oauth/v2/authorization?...ofile+r_emailaddress
Please check and do the needful at your end to fix the issue.