We have a custom module that receives messages from a Modbus Module but recently the messages started to not be delivered to the destination.
It was working fine until few days ago.
Looking at the edgeHub's log it apparently initializes correctly and then appears the following WARNINGS
<4> 2020-09-23 03:06:30.309 +00:00 [WRN] - Did not receive ack for message 8eba78ae-65f3-426f-97e6-d53681c99ab8 from device/module DEVICE_ID/MODULE_NAME
<4> 2020-09-23 03:06:30.342 +00:00 [WRN] - Error sending messages to module DEVICE_ID/MODULE_NAME
System.TimeoutException: Message completion response not received
at Microsoft.Azure.Devices.Edge.Hub.Core.Device.DeviceMessageHandler.SendMessageAsync(IMessage message, String input) in /home/vsts/work/1/s/edge-hub/src/Microsoft.Azure.Devices.Edge.Hub.Core/device/DeviceMessageHandler.cs:line 428
at Microsoft.Azure.Devices.Edge.Hub.Core.Routing.ModuleEndpoint.ModuleMessageProcessor.ProcessAsync(ICollection`1 routingMessages, IDeviceProxy dp, CancellationToken token) in /home/vsts/work/1/s/edge-hub/src/Microsoft.Azure.Devices.Edge.Hub.Core/routing/ModuleEndpoint.cs:line 166
<4> 2020-09-23 03:07:01.766 +00:00 [WRN] - Did not receive ack for message fbb1e347-d290-4527-9558-127f2d8f357d from device/module DEVICE_ID/MODULE_NAME
The Custom Module gets stuck in the first very message received from Modbus, and get it repeatedly.
However It does not impact it in receiving Command from the Cloud.
Our version of iotedge is 1.0.9.5 and the Microsoft.Azure.Devices.Client version is 1.25.0.