I’m using ASP.NET AJAX in the last project I work on and I’m very happy such control as Update Panel exists. Unfortunately today I experienced problem with validators inside Update Panel.
I have a form with some fields and validators. The validators are hidden by default.When the button is clicked the error messages appear above the form. I’m using validation summary to achieve this behaviour. When you submit the form for the first time everything’s working fine. But if you try to submit second time the validators’ error messages do not appear. Nothing is submitted to the server (so this means that the validator are working) but the error messages do not appear.
I tried to fix this on my own but without any success. Searching ASP.NET forums helped me to find the solution.
You can leave me a comment if this works for you.ajax, hidden, update panel validator