You're asking the user to cut and paste a URL... it's still too hard.

The one we use, when we need to, is this: http://supportdetails.com/

All they have to do is put a recipient email address in the top, and hit "send details", and we receive an email letting us know what they're using.

You can even pre-populate the form:

http://supportdetails.com/?recipient=your@email.com

http://supportdetails.com/?sender_name=Jessica&sender=email@...

Making it a single click function.

Although I agree with other comments in this thread, that this is something your app should log, there are scenarios in which this type of tool is really useful. Namely: Registration/Sign-in errors, in which it's going to be extremely difficult to identify from log files which tuple relates to the user having issues.