Sys.Browser.WebKit = {}; //Safari 3 is considered WebKit
if (navigator.userAgent.indexOf('WebKit/') > -1) {
    Sys.Browser.agent = Sys.Browser.WebKit;
    Sys.Browser.version = parseFloat(navigator.userAgent.match(/WebKit\/(\d+(\.\d+)?)/)[1]);
    Sys.Browser.name = 'WebKit';
}


Sys.WebForms.PageRequestManager.getInstance().add_endRequest(onEndRequest);

function onEndRequest(sender, args) {
    var error = args.get_error();
    if (error != null) {

        // Set the error handled flag to avoid a runtime error
        // reaching the user.
        args.set_errorHandled(true);

        // Remove the error name from the message
        var msg = error.message.replace("Sys.WebForms.PageRequestManagerServerErrorException: ", "");
        alert(msg);
    }
}