Hi,

I want to share the following scenario in the hope that it can be fixed by the Umbraco Forms developers.

Umbraco Forms (recent version) triggered an worker exception that can result in the shutdown of the app pool by IIS if this happens too often:

System.StackOverflowException was unhandled
Message: An unhandled exception of type 'System.StackOverflowException' occurred in System.Web.dll

I have found the cause and even though it can be fixed by setting the form values correctly I still would define this a bug.

The cause

Enter a condition on a form field that references (a value of) itself.

Scenario 1

• Check the conditions checkbox
• Enter a condition on a form field that references (a value of) itself.
• Add the form to a page and submit the form in the website
• Crash of IIS worker

Scenario 2

• Check the conditions checkbox
• Enter a condition on a form field that references (a value of) itself.
• No uncheck the 'Conditions' checkbox so you do not see the condition values anymore. A regular user will assume that conditions are no longer there.
• Add the form to a page and submit the form in the website
• Crash of IIS worker

I know that circular references can be hard to detect, but by better tracking of questions already processed it should be possible to at least show an recursion error instead of a stack overflow exception.

Also, when conditions are disabled on a question, these conditions should imho not be processed and should not trigger the stack overflow.

Regards, David