SVN update 403 error

Once in a while, when I update codes from SVN, I get the following error: Server sent unexpected return value (403 Forbidden) in response to OPTIONS request for 'https://jim@svn.domain.com/svnrepos' If I go to command line to run svn up, I get the following error: svn: E155036: Please see the 'svn upgrade' command svn: E155036: Working copy '/Users/jimz/Workshop/dev' is too old (format 10, created by Subversion 1.6) I might imply the SVN GUI tool uses different version from svn command line. I could not figure out the root cause of 403 Forbidden, but after I delete local Working copy, and checkout the whole folder, then it works. No root cause, but solution for quick turnaround.