A week ago we reported about an issue with the Sony A9 hot shoe. Here is an update with the exact serial numbers that are affected by this (via Sony). These camera will be repaired by Sony for free:
from 3020001 to 3023644
from 3320001 to 3320190
from 3370001 to 3381733
from 3770101 to 3777036
from 4470001 to 4475048
from 4870001 to 4871354
from 4970001 to 4973150
from 5070001 to 5076112
from 5670001 to 5670457