Azure Functions & Blob triggers - 404 The specified blob does not exist.

DBLJoey 51

I have setup a Azure Function with a Blob trigger. The Blobs are recognized by the trigger but the Azure Function using it can't find the Blob file. I use the InputStream as parameter in the main python function.

This is a screenshot of the log stream

And this is the main function in Azure Functions:

User's image

I have added the connection strings to the Azure Function Application settings.

What could be wrong in the setup here? Already tried to set up a new Azure Function but that didn't worked.

navba-MSFT 20,795 Reputation points Microsoft Employee

2023-07-31T03:35:05.2966667+00:00
@DBLJoey Welcome to Microsoft Q&A Forum, Thank you for posting your query here!

I understand that you are getting 404 The specified blob does not exist error while executing the BlobTriggered Azure Function.

Here are the few things you need to check:

Please check and confirm if this is working fine locally in your dev environment (before deploying it to Azure).

2.Could you please update your code as below to just print the blob name and blob length to ensure that it was able to fetch it correctly ?

def main(myblob: func.InputStream): logging.info(f"Python blob trigger function processed blob \n" f"Name: {myblob.name}\n" f"Blob Size: {myblob.length} bytes")

3.Please confirm which Python programming model you are using ? V1 or V2 ?

4.If you are using v1 programming model, You need to check your function.json and ensure that you have the necessary settings like below:

{ "scriptFile": "__init__.py", "bindings": [ { "name": "myblob", "type": "blobTrigger", "direction": "in", "path": "MySampleContainer/{blobname}", "connection": "MyStorageConnectionString" } ] }

Here the path option defines the path for the blob storage where we are listening to. Currently, we are listening to all new files created in the blob storage path MySampleContainer/. I hope you have added the right container name here.
Also check if the connectionstring of the right Storage account is added.

5.If you are using v2 programming model, you could try with the below sample code:

import logging import azure.functions as func app = func.FunctionApp() @app.function_name(name="BlobTrigger1") @app.blob_trigger(arg_name="myblob", path="PATH/TO/BLOB", connection="CONNECTION_SETTING") def test_function(myblob: func.InputStream): logging.info(f"Python blob trigger function processed blob \n" f"Name: {myblob.name}\n" f"Blob Size: {myblob.length} bytes")

Please confirm if that blob exists in storage ? If it does, you can try with uploading a blob with try with a simple blob name like test.txt and check if that works ?

If the above action plan doesn't help, Please let me know, I would be happy to help.

** Please do not forget to "Accept the answer” and “up-vote” wherever the information provided helps you, this can be beneficial to other community members.
DBLJoey 51 Reputation points

2023-08-01T12:36:04.3933333+00:00

Thanks for your response. The weird thing is, i (still) receive the message that the Blob file could not be found. But in the Function Monitor in the Azure Function it sees the Blob file and runs as succeeded. So i am not sure the problem is fixed. The log is saying it could not be found but the Azure Function runs. Seems to be unstable.
navba-MSFT 20,795 Reputation points Microsoft Employee

2023-08-01T12:39:29.2233333+00:00

@DBLJoey Thanks for getting back. Could you please let me know the status of the above action plans I had shared ? That will help us to isolate this issue.
DBLJoey 51 Reputation points

2023-08-01T12:49:54.08+00:00
Hi i tried your steps;

I tested it locally, that worked.

I received the 404 in the log stream of the Azure function. But it still runs in de Monitor logs as succeeded

I am using the v1 programming model

I checked the settings, in de function.json and double checked the connection string setting in the Azure Function

I can confirm that the blob storage exists

So, the weird thing is that my script is working, it processes the file but the log stream is saying the blob doesn't exists.
DBLJoey 51 Reputation points

2023-08-01T13:00:56.45+00:00

This is with a very small file (test.json). And your main() script. The log stream is 404.

And this is the status in de Monitor logs;
navba-MSFT 20,795 Reputation points Microsoft Employee

2023-08-01T13:05:05.05+00:00

@DBLJoey Thanks for the update. Looking at the monitor screenshot, I see that the sucess message with the blob properties. So I am glad that it is working. Regarding the warning in the File system Stream logs, I am looking at the Storage request ID, which You have shared in your screenshot. I will look at our backend logs and check the details and update you.

Accepted answer

navba-MSFT 20,795 Reputation points Microsoft Employee

2023-08-04T04:33:19.9566667+00:00

@DBLJoey Appreciate your patience on this. I had a look at the backend logs for the above failure ( using the storage request ID). I see that the 404 error was for the Get Blob Properties operation. This is a HEAD call that goes first and checks if the blob exists or not after that the actual blob operation happens. This is by-design. This being a warning and not a fatal error, it can be safely ignored. This warning will not affect the function execution / blob operation.

Note that there is no way to turn off the tracking for storage call as Storage SDK will be doing this for us for the most part and this cannot be turned off.
In case someone wants to disable all the Dependency Tracking then you can set the enableDependencyTracking to false for the Application Insights in case you don't need it. This can be done in the host.json file.

"enableDependencyTracking":"false"

Similar was discussed here too.

**
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Azure Functions & Blob triggers - 404 The specified blob does not exist.

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