Please see this post
Hi Clyde,
Thanks for the response. Your link does not help because it refers to HTML addresses with waypoint NAMES giving problems with question marks, etc. However, you used to allow Waypoint CODES (eg GCMMYR or GC9331, etc) to be used. These are controlled codes as used by GC.com and do not have any special characters in them.
I understand that there may be other geocaching sites with different schemes that might cause a problem, but if I only use GC.com then it would be really nice to have a user option to select GCxxxx.HTML as the final part of the URL address.