It looks like it has something to do with Optional features>>reconnect. I turned it off and no more crashes.
With Reconnect feature ON, our client experienced endless (at least 4 times in a row) Rebuild Stock maintenances:
The maintenance finishes and starts again after the user is reconnected:

2021-06-03 17:15:26 AVA Maintenance RebuildStockMn
2021-06-03 17:15:26 AVA Database set to unsafe (import and maintenance) mode
2021-06-03 17:15:26 AVA Database set to unsafe (import and maintenance) mode
2021-06-03 17:20:35 AVA Database set to safe (normal) mode, flushing cache...
2021-06-03 17:20:35 AVA Database set to safe (normal) mode, flushing cache...
2021-06-03 17:20:35 AVA GetThreadRepCancel() = true -- SendROData(): SendDataSV() Failed 2
...
2021-06-03 17:20:36 Database not in Live Mode
2021-06-03 17:20:36 SYSTEM Logoff 10.78.254.182:51595: the client closed the connection (2)
2021-06-03 17:20:36 AVA Login @10.78.254.182 << automatic reconnect

2021-06-03 17:20:37 AVA Maintenance RebuildStockMn < 2021-06-03 17:20:37 AVA Database set to unsafe (import and maintenance) mode
2021-06-03 17:20:37 AVA Database set to unsafe (import and maintenance) mode