Azure Function Timer Trigger Connection string error

Scott Rowles 1

I have created the default .net core Windows timer trigger app in a new function app as a single function all by itself. Before I change ANYTHING in the function, the default function throws the following error:

2020-12-08T14:31:47.515 [Error] Executed 'Functions.CloudAssetHeartbeat' (Failed, Id=0128e6c3-d021-4763-9cad-1be5fe3c7001, Duration=0ms)Value cannot be null. (Parameter 'connectionString')

I have deleted the function and recreated. I have deleted the function app and recreated. I have added additional code to the function.

Everything results in the same error.

I do have another function app with multiple functions running just fine as a powershell core in the same subscriptions.

MayankBargali-MSFT 70,461 Reputation points

2020-12-08T15:25:06.517+00:00

Hi @Scott Rowles

As per the error message, there is a parameter named 'connectionString' in your function app and the value is passed as null.
Please verify in your code if you have defined parameters and check if you have defined the same in the Configuration --> Application settings of your function app. Also, verify if you are communicating with the storage account from your azure function.
Scott Rowles 1 Reputation point

2020-12-08T15:52:32.193+00:00
This is the entirety of my function:

using System; public static void Run(TimerInfo myTimer, ILogger log) { log.LogInformation($"C# Timer trigger function executed at: {DateTime.Now}"); }

There is NO parameter anywhere named connection string
MayankBargali-MSFT 70,461 Reputation points

2020-12-08T15:58:18.883+00:00

@Scott Rowles Is this the only code in your function app? Or there are any other methods?
Scott Rowles 1 Reputation point

2020-12-08T15:59:20.903+00:00

That is it. I have deleted the function, I have deleted the function app. I have added a line of code to write something else to the log. I get the same error every time.
Jaliya Udagedara 2,821 Reputation points MVP

2020-12-10T09:26:25.78+00:00

This is interesting. I just tried and it worked for me.

Found a similar thread: When creating a Timer Trigger function from the portal I receive Value cannot be null. (Parameter 'connectionString') error

@MayankBargali-MSFT , believe this needs to be investigated further. Maybe this can be an edge case based on parameters selected when creating the function app.
MayankBargali-MSFT 70,461 Reputation points

2020-12-10T10:03:40.577+00:00

@Jaliya Udagedara Thanks for your response. I am working with @Scott Rowles offline and waiting for his confirmation if the suggestion has helped and will be posting the answer.
Jaliya Udagedara 2,821 Reputation points MVP

2020-12-10T16:29:50.953+00:00

Awesome, really keen to know what happened!

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Azure Function Timer Trigger Connection string error

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