I am trying to efile extension. I received this error. I saw a fix from a earlier post. where I deleted and entered a new preparer it didn't work. Unless I missed something

Your request was not understood by the e-filing service. - Invalid XML. cvc-complex-type.2.4.a: Invalid content was found starting with element 'app'. One of '{senderEmail, legalName}' is expected. Please verify that your application program is up-to-date. Problem occurred transmitting efile data.