var ERR_MESSAGE = 'Oops, there was an error processing your request.\n Please try again later.'

$(document).ajaxError(function errorHandler(event, xhr, ajaxOptions, thrownError) {
    alert(ERR_MESSAGE + "\n\rCode: 567GWE\n" + thrownError);
});

try{
    var prm = Sys.WebForms.PageRequestManager.getInstance();
    prm.add_endRequest(errorHandling);
}
catch(err){
 //We assume no ms ajax support. Do nothing
}

function errorHandling(sender, args) {
    if (args.get_error() != undefined) {
        alert(ERR_MESSAGE + "\n\rCode: 1T74JB\n " + args.get_error());
        args.set_errorHandled(true);
    }
}