After deploying a ASP.NET WebForms application to a production server some of the ajax calls has stopped working for me. After some debugging I found out that the following statement (in the internal client-method WebForm_DoCallback) was causing the problem:

xmlRequest.open("POST", action, true);

The problem seemed to be that the action-variable was empty so after checking the rendered html I found out that the form-tag rendered on the production server looks like:

<form method="post" action="" id="Form1">

However, on my developer machine I get the following:

<form method="post" action="default.aspx" id="Form1">

So, why would the action-attibute render on my dev.machine but not on the production server? This seems to be the case only for one specific web form, when I look on other pages the action-attribute renders correctly.

Any suggestions or ideas would be helpful!