Error in Azure Functions leading to Azure Functions unreachable

Question

Hi, I suddenly encountered the error 'Azure.Messaging.EventHubs: The path to an Event Hub may be specified as part of the connection string or as a separate value, but not both. Please verify that your connection string does not have the ‘EntityPath’ token if you are passing an explicit Event Hub name. (Parameter: connectionString)' in Azure Functions leading to 'Azure Functions runtime is unreachable' and it didn't happen before. Can someone explain to me what caused this error and how to solve it. By the way I am doing it on the web instead of VS. Thank you in advance!

Answer 1

Thank you for adding more information in the comments of my other answer. I reproduced the error, it's not something you did, it's an error in the Azure Portal! To fix it, follow these steps:

1. Go to the Configuration of your Function.
In your Function app, select Configuration on the left (under Settings). You will see the application settings of your function. Locate the key that has your IoT Hub name and the _events_IOTHUB suffix. (e.g. if your hub is named best-hub-ever, look for the key best-hub-ever_events_IOTHUB.

Click on the Edit icon, you need to copy the text after ;EntityPath=. (The key is best-hub-ever in the screenshot)

2. Go to your **Function (select Functions, then your Function) and go the Code + Test screen.**
You will see a dropdown, click on it and select function.json

When you do, you will notice the configuration is incorrect. The eventHubName is set to samples-workitems. Change this value to the value you copied in step 1. Click on save.

Hit save, restart the Function App for good measure, everything should be working again.

Answer 2

An event hub connection string looks like this:

Endpoint=sb://somehub-421337-f5aa4abe16.servicebus.windows.net/;SharedAccessKeyName=iothubowner;SharedAccessKey=ASdhwa883ajhwd/+rX+6m3+FNGoE=;EntityPath=event-hub-name  

At the end, you'll find EntityPath=event-hub-name; this specifies the event hub name. You can leave this out of the connection string if you specify it somewhere else in the Event Hub Trigger binding in your function. You did not specify a programming language, so I'll give the example in C#:

[FunctionName("EventHubTriggerCSharp")]  
public void Run([EventHubTrigger("event-hub-name", Connection = "EventHubConnectionAppSetting")] EventData[] eventHubMessages, ILogger log)  

In this binding, the name of the event hub is specified in the trigger "event-hub-name". So you would leave the event hub name out of the connection string. The connection string will become:

Endpoint=sb://somehub-421337-f5aa4abe16.servicebus.windows.net/;SharedAccessKeyName=iothubowner;SharedAccessKey=ASdhwa883ajhwd/+rX+6m3+FNGoE=