The account and password I use on my desktop browser does not work on my xfinity mobile app. How do I get this resolved?
Please sign in with the email that you provided at the time XFINITY Home was installed 
Well doh! that's what I am using! SHEEEEZ!
Just confirmed I can login on a web page on my mobile device, but cannot login to any of the xfinity apps.
(friendly sidbar: I would enter a an acronym here for what the fizzle, but you cannot enter this acronym as 3 letters ! possibly due to acronymphomaniacs? Dear Glinda...)
Also tried clearing the cache for the app and restarting it, still says account and password do not match.
Most likely researched solution is here: http://forums.xfinity.com/t5/Comcast-ID-and-Sign-In/My-Account-APP-won-t-allow-login/m-p/2602666#M30... if only I could get someone in support to figure out how to check for me.
The most irksome part is that I've used this app before.
Current work around: uninstall and deprecate use of this app. buh bye
I pulled up your account & see that you are not a current subscriber of the Xfinity Home security service. This is the source of the 42401 error.
The link you posted is regarding an issue signing into the My Account app. Is the My Account app what you'd meant to download? This help article will link you to the My Account apps for iOS & Android: http://customer.xfinity.com/help-and-support/xfinity-apps/get-my-account-app/