iOS Question Problems with installed iPhones

[Stephenz43]

Greetings

I have a small project installed on 3 iphones and a iPad. The devices are as follows, iphone6, iphone8, iphone11 and ipad ? . The app has worked for a few years. Yesterday , both the iphone6 and iphone8 stopped working. The ipad and iphone12 both are continuing to working fine. I did notice that the Apple Developers account was expired by a few days and immediately paid it current. Can anyone comment what happened

Any help would be appreciated

 

[Erel]

As the apps were not installed from the app store, they must be compiled with a valid certificate. You need to compile the app again.