Official Facebook Hello contacts/dialer app login only says "104"

Question

The Facebook Hello app https://newsroom.fb.com/news/2015/04/introducing-hello (released April 22, 2015 according to their post) is giving an error only saying "incorrect signature" and "104".

I am a good/loyal Facebook user so I installed the apps they suggested, grew to love using Facebook Hello the officially advocated contacts program, and now after searching several times over a year for news and not finding any clear Help article (I found a lot of still-posted promotional pieces about how great "Hello" is as the first, second, and third, result!) I am wondering what do you do?

Customer reviews at https://play.google.com/store/apps/details?id=com.facebook.phone&rdid=com.facebook.phone&reviewId=gp%3AAOqpTOHZWFKjSnnjN5CrK5pmMl558_uC7NiCPu9pWIWcATy8WwuYkGe9IRmfOisfZN2fS3dlIh2cGaGO-2I&showAllReviews=true show many people also just reported a "104".

Answer 1

"We're moving on" is all Facebook has said since then, adding "We will be deprecating Hello in a few weeks." minus a reason, from an unknown anonymous Facebook employee author.

For some reason Facebook did not tell users who installed the HEAVILY advertised "Hello Dialer" application about (maybe with another ad equally) that they're forgetting the idea now: https://newsroom.fb.com/news/2018/07/hello-tbh-moving-on/.

The reason you did not find information, is that recent news suggests the application in question has been deprecated officially in a quiet press release, in their news article I archived to report at http://web.archive.org/web/20190522194837/https://newsroom.fb.com/news/2018/07/hello-tbh-moving-on because of the secrecy, as that is fairly well hidden for a large organization, and had not been given good meta-data information, to be indexed in searches with priority.