Apparently the most recent upgrade to IOS 12.3.1 has changed something in the charging software in my 5S.
I use a Vivitar 15000mAh external battery as my charging device and apparently it has some electronics(Computer ?) inside the case that the phone now recognizes and says that this in not a valid charging device.
Well, it worked great until my latest upgrade. Apple should be notified of this but I don’t know how