I found an item, but it looks that it's closed? I have the same problem http://www.nabble.com/--htmlunit-Bugs-1845438---__doPostBack-support-under-webtestcanoo-1644-td14749042.html
Example, I've just created a new user for this. http://www.fotocasa.es/area-personal__fotocasa.aspx?S42: user: [EMAIL PROTECTED] password: [EMAIL PROTECTED]<http://www.fotocasa.es/area-personal__fotocasa.aspx?S42> JavaScript error loading page http://www.fotocasa.es/area-personal__fotocasa.aspx?S42: ReferenceError: "WebForm_DoPostBackWithOptions" is not defined. (onclick event for HtmlSubmitInput[<input type="submit" name="ctl00$ContentPlaceHolder1$uie_LoginControl$btn_Login" value=" Ir " onclick="javascript:WebForm_DoPostBackWithOptions(new WebForm_PostBackOptions("ctl00$ContentPlaceHolder1$uie_LoginControl$btn_Login", "", true, "Login", "", false, false))" id="ctl00_ContentPlaceHolder1_uie_LoginControl_btn_Login" title=" Ir " class="btn">]#1) Details javascript errorReferenceError: "WebForm_DoPostBackWithOptions" is not defined. (onclick event for HtmlSubmitInput[<input type="submit" name="ctl00$ContentPlaceHolder1$uie_LoginControl$btn_Login" value=" Ir " onclick="javascript:WebForm_DoPostBackWithOptions(new WebForm_PostBackOptions("ctl00$ContentPlaceHolder1$uie_LoginControl$btn_Login", "", true, "Login", "", false, false))" id="ctl00_ContentPlaceHolder1_uie_LoginControl_btn_Login" title=" Ir " class="btn">]#1) line1 javascript sourcefunction () { [native code, arity=0] } failing linefunction () { javascript call stackReferenceError: "WebForm_DoPostBackWithOptions" is not defined. (onclick event for HtmlSubmitInput[<input type="submit" name="ctl00$ContentPlaceHolder1$uie_LoginControl$btn_Login" value=" Ir " onclick="javascript:WebForm_DoPostBackWithOptions(new WebForm_PostBackOptions("ctl00$ContentPlaceHolder1$uie_LoginControl$btn_Login", "", true, "Login", "", false, false))" id="ctl00_ContentPlaceHolder1_uie_LoginControl_btn_Login" title=" Ir " class="btn">]#1) at (onclick event for HtmlSubmitInput[<input type="submit" name="ctl00$ContentPlaceHolder1$uie_LoginControl$btn_Login" value=" Ir " onclick="javascript:WebForm_DoPostBackWithOptions(new WebForm_PostBackOptions("ctl00$ContentPlaceHolder1$uie_LoginControl$btn_Login", "", true, "Login", "", false, false))" id="ctl00_ContentPlaceHolder1_uie_LoginControl_btn_Login" title=" Ir " class="btn">]:1)
