"LG IMS keeps stopping"

Both of our LG phones started getting the "LG IMS Keeps Stopping" popup every three seconds starting yesterday.  I followed the instructions on a half-dozen YouTube videos exactly, and NONE of them had any effect.  Then I checked a half-dozen forums and followed all their advice (except a factory reset) and NONE of them had any effect.

Unfortunately, it appears that some folks on YouTube are exploiting this problem by posting "fixes" that they have not tested or confirmed, because all they want is the views and the clicks.  They know that desperate users will watch the video to the end, even though it does not work.

Evidently T-Mobile changed something on Sunday that makes the LG IMS system app "stutter" (but not stop) every three seconds.  That is apparent because the phone can still send/receive voice calls and text messages, and "clearing the cache" and "force stopping" only works for a few seconds before the app resets and attempts to function again -- triggering that endless popup message every three seconds!

LG has stopped making phones, but supposedly promised support for a couple more years.  T-Mobile and LG have been mum on the problem so far, even though it evidently affects just about every LG phone on T-Mobile -- that could be hundreds of thousands.

It is frustrating that the forums and YouTube are full of false fixes, and the minor news coverage so far says “a small number” are affected (which is not true).