Azure Function .NET 9 Isolated makes huge amount of requests to Azure Blob storage with "Not found" response code

Hello @Zaskevich Ivan,
It seems that your Azure Functions are attempting to access blob storage paths that do not exist, which is resulting in a high number of "Not Found" responses. This behavior could be attributed to the expected structure of the blob storage paths for timer-triggered functions.

In Azure Functions, the host uses specific paths to track the state of timer triggers. If the expected files are not present in the specified path, the function will continuously attempt to access them, leading to an increased number of requests and consequently higher costs.

The discrepancy in the expected and actual blob path structure indicates that there may have been a change in how the function app is managing its timer state or an issue with the deployment that has led to the incorrect path being referenced.

To mitigate this issue, you could consider the following steps:

• Ensure that the blob storage structure is correctly set up according to the expected paths for your timer functions.
• Review any recent changes to your function app or deployment process that may have affected the blob storage paths.
• If renaming the folder temporarily resolved the issue, it may be worth investigating why the function is not recognizing the correct path.

For further clarification, please refer to the following documentations:

https://learn.microsoft.com/en-us/azure/azure-functions/functions-recover-storage-account

https://learn.microsoft.com/en-us/azure/azure-functions/storage-considerations?tabs=azure-cli#host-id-considerations

I hope this helps resolve your issue. Feel free to reach out if you have further concerns.

Hello @Zaskevich Ivan,
Just checking in to see if above information was helpful. If you have any further updates on this issue, please feel free to post back.

Hi Ranashekar Guda,
Thanks for your answer very much.
I haven't fixed the issue yet, but I've found strange thing during investigation.

I created new Function project using Visual Studio 2022 Template (version 17.13.4) without any changes from my side.
The project contains one TimerTrigger function

Csproj file:

Also I've created new Azure Function running on .NET9 and deployed new project to this Azure resource.

So, on start Azure Function created the folder "timers/es-testing-function/Host.Functions.Function1/" in connected Blob storage.
But in the same time I see GetBlob call to folder "ESTestingFunction.Function1.Run" in storage's logs. This requests fail with 404 Status Code (requests are sent every 10 second).

Also according the logs Azure function uses 2 different versions of the azsdk-net-Storage.Blobs package

Also I tried to create missed folder believing that it can reduce the amount of the requests, but without any success

So right now I have several questions:

1. Why function use 2 versions of the the azsdk-net-Storage.Blobs package. Is this expected?
2. Why after each function call file timers/es-testing-function/Host.Functions.Function1/status is update, but reading happens in folder timers/es-testing-function/ESTestingFunction.Function1.Run/status. Is it expected?
3. Is it expected that Azure Function reads status file every 10 seconds?
4. Is it expected that even I've created function running on .NET 9, I see that .NET 8 is mentioned in logs file?

Hello @Zaskevich Ivan,
I have reached out to you over private message could you please check and help me with requested information to assist you further on this.