The specified path, file name, or both are too long. The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters.
If you run into this it could be because your url is too long for the routing engine to handle by default.
all you gotta do is find your httpruntime configuration element in your web.config and set an attribute called relaxedUrlToFileSystemMapping in it to true, like this:
<httpRuntime targetFramework=”4.5″ maxRequestLength=”512000″ relaxedUrlToFileSystemMapping=”true” />