If you haven’t made the above mistake and still see the same error, then perhaps the directory specified for SVNPath may not be really a SVN repository path. Otherwise you might have forgotten to initialize the fresh directory which is created for SVN repository. You can use the following commad to initialize SVN repository for the first time.
svnadmin create /project/svn
The above command takes “/project/svn” as an example, you should replace it with whatever directory you specified for SVNPath in Apache configuration.