Azure Function App. moving messages to posion queue with no errors, warnings or exceptions

Nat Mohan 1 Reputation point

We have an Linux based queue triggered Python Azure Function App. running on consumption plan. We have a process on another server to ingest about 4 to 5 queue message per second which can go up to a couple of thousand messages put in the queues in a span of 15 minutes. The Azure function app processes the queue messages and outputs the data to blob storage as expected by auto scaling and processing messages in parallel. 95% of the messages are successfully processed and then it stops invoking the messages and directly moves them to poison. Invariably, this happens while processing the last few batches of messages. I checked the invocation logs and also end to end transactions and it looks like there was no invocation after '2021-10-06 17:49:38.123' (UTC) and messages were being moved to poison queue for five minutes after the last successful invocation. I couldn't find any exception recorded in transaction/failure logs (EST). It looks like the function app instances shuts down refusing to process the last few messages. I looked up on the internet and found an issue related to what I am experiencing. I am unsure if this is a known issue or if there's something wrong with my host.json file. Attaching the necessary screenshots. Thanks in advance.


"version": "2.0",
"logging": {
"applicationInsights": {
"samplingSettings": {
"isEnabled": true,
"excludedTypes": "Request"
"extensionBundle": {
"id": "Microsoft.Azure.Functions.ExtensionBundle",
"version": "[2.*, 3.0.0)"
"extensions": {
"queues": {
"maxPollingInterval": "00:00:01",
"maxDequeueCount": 1,
"newBatchThreshold": 8,
"batchSize": 4
"retry": {
"strategy": "fixedDelay",
"maxRetryCount": 1,
"delayInterval": "00:00:01"


Azure Functions
Azure Functions
An Azure service that provides an event-driven serverless compute platform.
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