Bad Error Message

Hi .

I've just came across a site , which gave me the following error message in the process of registration .
( And it's not just a site of some kid .. it's a site related to sport bets and online casino )

Message is in Hebrew and it says :
"Attention - One or more fields in the form has illegal character."











I just wonder .. whoever wrote the validations for this form, probably knows ( in code) which field is the troublemaker.
So .... why !?! why ?!? why !?!?! to hide this time-saving info from the user.
Let's say that for some reason (??? ) you don't know which field is it .
So maybe give me the bad character .. and I'll go over the 20 fields in the form and find it.
Give me something !!!