// _pendingCallbacks[...] is null or not an object bug fix:

if (typeof (WebForm_CallbackComplete) == "function") {
  // set the original version with fixed version
  WebForm_CallbackComplete = WebForm_CallbackComplete_SyncFixed_AddressFinder;
}

function WebForm_CallbackComplete_SyncFixed_AddressFinder() {
    // SyncFix: the original version uses "i" as global thereby resulting in javascript errors when "i" is used elsewhere in consuming pages
    for (var i = 0; i < __pendingCallbacks.length; i++) {
        callbackObject = __pendingCallbacks[i];
        if (callbackObject && callbackObject.xmlRequest && (callbackObject.xmlRequest.readyState == 4)) {
            // the callback should be executed after releasing all resources 
            // associated with this request. 
            // Originally if the callback gets executed here and the callback 
            // routine makes another ASP.NET ajax request then the pending slots and
            // pending callbacks array gets messed up since the slot is not released
            // before the next ASP.NET request comes.
            // FIX: This statement has been moved below
            // WebForm_ExecuteCallback(callbackObject);
            if (!__pendingCallbacks[i].async) {
                __synchronousCallBackIndex = -1;
            }
            __pendingCallbacks[i] = null;
            var callbackFrameID = "__CALLBACKFRAME" + i;
            var xmlRequestFrame = document.getElementById(callbackFrameID);
            if (xmlRequestFrame) {
                xmlRequestFrame.parentNode.removeChild(xmlRequestFrame);
            }
            WebForm_ExecuteCallback(callbackObject);
        }
    }
}