I am using Coldfusion 6.1 on an Apache server, but I have also seen the problem happen with Coldfusion 5.0 under IIS.
Passing a bunch of form parameters from one template to another (in this case including some WDDX packets and in a secure environment) - occassionaly, say one in ten times, the receiving template states that a form variable is undefined, and on inspection, no form parameters are defined. Refreshing the page, or going back and resubmitting the form, normally sorts the problem out and they come through fine. The problem is not affected by the contents of the form variables - you can use exactly the same inputs - most of the time they get through, sometimes they don't. The problem only seems to occur from some client machines, but I haven't been able to pin-down a commonality between machines yet.
The problem seems to occur more if there are a lot of form variables and it may be affected by being on a secure server - but it is annoyingly inconsistent. It only happens on some servers - same code works fine elsewhere. Maybe the broswer/OS/firewall is having some effect?
I know I can trap the problem by using IsDefined() but I can't automatically reload without the browser throwing a warning dialogue or by jumping the user back to the form and asking them to hit submit again (neither of which inspire confidence in a secure checkout).
I am an experienced Coldfusion programmer and have eliminated all other possible programming errors - this is definately an inconsistent bug.
Is this a known bug? Is there a known fix?
Thanks in advance