Well, a "%" (percent sign) is a character used for url encoding (read this
http://en.wikipedia.org/wiki/Percent-encoding[
^]), so you can not us it on its own. To understand your error it is important to know what comes after the percent sign, because this is the encoded information. like %20 is a space character, %23 is a #, and so on...
hopefully you are not mistaken with the hash (#) which can, and often is used for routing in an url!
hope this helps