Function App not waiting for the response from other function app

Question

Function App not waiting for the response from other function app

AJITHKRISHNAMANKENA-7942 0

I have 2 Azure Function apps. Lets say Function App A and Function App B. Function App A is a .Net 8 and Function App B is Python 3.12. Function App A is having a timer trigger whose functionality is to connect to multiple azure resources and perform required operations. At the last it would be calling this Python Function App B (via Http Post Call) by sending some data for processing and receives the data after processing. Once Function App A receives data from function app B then Function App A saves data into DB and the timer trigger operation is done.

Here the Function App B takes an average of 4 to 5 minutes to process the data received from Function App A. Here the function app A is waiting for 1 Minute 40 Seconds and terminating the execution. Even though the service call to function app B is an await call, Function App A is not waiting for the response from Function App B.

Could you share any suggestions to make the Function App A wait until it receives the response from Function App B?

Your support is highly appreciated.

Thank you in advance😊

Deepanshukatara-6769 16,565 Reputation points Moderator

2025-06-20T06:51:18.3866667+00:00
Hello , Welcome to MS Q&A

Pls check below action points

Increase HttpClient Timeout in Function App A

HttpClient.Timeout Property (Microsoft Docs)

Best practices for using HttpClient in .NET

Set Azure Function Timeout

Azure Functions host.json reference - functionTimeout

Timeouts in Azure Functions

Review Azure Functions Hosting Plans

Azure Functions hosting options

Premium plan for Azure Functions

Choose the right Azure Functions plan

Use Asynchronous Patterns for Long-running Operations

Azure Durable Functions (Orchestrations)

Azure Functions Bindings - Azure Storage Queues

Best practices for long-running Functions

Pls check above and let me know if any further ques

Kindly accept if helps

Thanks

Deepanshu
Ripin 11 Reputation points

2025-06-20T19:28:09.69+00:00
It seems like, the Function App A is timeout before unction App B can respond. You can change the Timout of the Function App A.

Azure Functions can now run up to 10 minutes using the consumption plan by adding the functionTimeout setting to your host.json file.

// Value indicating the timeout duration for all functions. // Set functionTimeout to 10 minutes { "functionTimeout": "00:10:00" }
AJITHKRISHNAMANKENA-7942 0 Reputation points

2025-06-21T04:04:34.7966667+00:00

Hi Deepanshu,

Thank you for sharing you insights on the issue.

I have tried HttpClient.Timeout Property (Microsoft Docs) & increase the HttpClient Time out to 10 mins. When implemented and tested, function app is waiting more than 1 Minute 40 seconds. Out of many testing scenarios, only 2 times I am able to receive response from function app B.

Here is how it went - Function App A is waiting till Function App B is sending the response. The moment Function App B responded back, I couldn't see any logs in Function App A on receiving the response. All I could see is Executed timer trigger(which usually shows when timer trigger completes execution), its just terminating the execution without executing further lines of code after the service call to Function App B. But couple of times I could see Function App A waiting for the response from B and executing further steps in Function App A once the response is received.

FYI - I am using P0V3 version of App Service Plan. I have time out of 1 hour defined in host.json. The call to Function App B is an async call.
AJITHKRISHNAMANKENA-7942 0 Reputation points

2025-06-21T04:07:35.19+00:00

Hi Ripin, Thank you for looking into the issue.

The function time out is 1 hour configured in host.json, still facing the same issue with 1 hour time out.
Loknathsatyasaivarma Mahali 2,740 Reputation points Microsoft External Staff Moderator

2025-06-23T01:46:46.1066667+00:00
Hello AJITHKRISHNAMANKENA-7942,

Thanks for provide the more information on the issue, could you please try the below step and please let us know the output so that we can guide you accordingly.

To handle long-running HTTP calls in your .NET 8 Azure Function App, use IHttpClientFactory with a custom timeout:

1. Configure named HttpClient in Program.cs:

builder.Services.AddHttpClient("FunctionBClient", client => { client.Timeout = TimeSpan.FromMinutes(10); });

2. Use it in your timer-triggered function:

var client = _httpClientFactory.CreateClient("FunctionBClient"); var response = await client.PostAsJsonAsync("<FunctionB URL>", payload);

This ensures your function can wait up to 10 minutes for a response without timing out.
Also, for your better understanding please refer this Dependency injection, HttpClient.Timeout Property documents.
Loknathsatyasaivarma Mahali 2,740 Reputation points Microsoft External Staff Moderator

2025-06-24T06:05:11.09+00:00

Hello AJITHKRISHNAMANKENA-7942,

I wanted to check if the information provided above has helped you understand better. If you have any further concerns, please feel free to share them here.
AJITHKRISHNAMANKENA-7942 0 Reputation points

2025-06-25T04:38:50.4733333+00:00

Hi Deepanshu, Ripin, Loknath,

Thank you for helping me on the issue.

I have tried https://learn.microsoft.com/dotnet/api/system.net.http.httpclient.timeout?view=net-8.0 to increase the httpcleint timeout, which helped me resolve the issue.

1 answer

Your answer

Deepanshukatara-6769 16,565 Reputation points Moderator

2025-06-20T06:51:18.3866667+00:00

Hello , Welcome to MS Q&A

Pls check below action points

Increase HttpClient Timeout in Function App A

HttpClient.Timeout Property (Microsoft Docs)

Best practices for using HttpClient in .NET

Set Azure Function Timeout

Azure Functions host.json reference - functionTimeout

Timeouts in Azure Functions

Review Azure Functions Hosting Plans

Azure Functions hosting options

Premium plan for Azure Functions

Choose the right Azure Functions plan

Use Asynchronous Patterns for Long-running Operations

Azure Durable Functions (Orchestrations)

Azure Functions Bindings - Azure Storage Queues

Best practices for long-running Functions

Pls check above and let me know if any further ques

Kindly accept if helps

Thanks

Deepanshu
Ripin 11 Reputation points

2025-06-20T19:28:09.69+00:00

It seems like, the Function App A is timeout before unction App B can respond. You can change the Timout of the Function App A.

Azure Functions can now run up to 10 minutes using the consumption plan by adding the functionTimeout setting to your host.json file.

// Value indicating the timeout duration for all functions. // Set functionTimeout to 10 minutes { "functionTimeout": "00:10:00" }
AJITHKRISHNAMANKENA-7942 0 Reputation points

2025-06-21T04:04:34.7966667+00:00

Hi Deepanshu,

Thank you for sharing you insights on the issue.

I have tried HttpClient.Timeout Property (Microsoft Docs) & increase the HttpClient Time out to 10 mins. When implemented and tested, function app is waiting more than 1 Minute 40 seconds. Out of many testing scenarios, only 2 times I am able to receive response from function app B.

Here is how it went - Function App A is waiting till Function App B is sending the response. The moment Function App B responded back, I couldn't see any logs in Function App A on receiving the response. All I could see is Executed timer trigger(which usually shows when timer trigger completes execution), its just terminating the execution without executing further lines of code after the service call to Function App B. But couple of times I could see Function App A waiting for the response from B and executing further steps in Function App A once the response is received.

FYI - I am using P0V3 version of App Service Plan. I have time out of 1 hour defined in host.json. The call to Function App B is an async call.
AJITHKRISHNAMANKENA-7942 0 Reputation points

2025-06-21T04:07:35.19+00:00

Hi Ripin, Thank you for looking into the issue.

The function time out is 1 hour configured in host.json, still facing the same issue with 1 hour time out.
Loknathsatyasaivarma Mahali 2,740 Reputation points Microsoft External Staff Moderator

2025-06-23T01:46:46.1066667+00:00

Hello AJITHKRISHNAMANKENA-7942,

Thanks for provide the more information on the issue, could you please try the below step and please let us know the output so that we can guide you accordingly.

To handle long-running HTTP calls in your .NET 8 Azure Function App, use IHttpClientFactory with a custom timeout:

1. Configure named HttpClient in Program.cs:

builder.Services.AddHttpClient("FunctionBClient", client => { client.Timeout = TimeSpan.FromMinutes(10); });

2. Use it in your timer-triggered function:

var client = _httpClientFactory.CreateClient("FunctionBClient"); var response = await client.PostAsJsonAsync("<FunctionB URL>", payload);

This ensures your function can wait up to 10 minutes for a response without timing out.
Also, for your better understanding please refer this Dependency injection, HttpClient.Timeout Property documents.
Loknathsatyasaivarma Mahali 2,740 Reputation points Microsoft External Staff Moderator

2025-06-24T06:05:11.09+00:00

Hello AJITHKRISHNAMANKENA-7942,

I wanted to check if the information provided above has helped you understand better. If you have any further concerns, please feel free to share them here.
AJITHKRISHNAMANKENA-7942 0 Reputation points

2025-06-25T04:38:50.4733333+00:00

Hi Deepanshu, Ripin, Loknath,

Thank you for helping me on the issue.

I have tried https://learn.microsoft.com/dotnet/api/system.net.http.httpclient.timeout?view=net-8.0 to increase the httpcleint timeout, which helped me resolve the issue.

Answer 1

Hello AJITHKRISHNAMANKENA-7942,

Thank you for your patience and for sharing your feedback on the Q&A community platform. I’m glad to hear that you were able to resolve your issue, and I appreciate you sharing your solution! Your contribution is valuable and can help others in the community facing similar challenges.

As per the Microsoft Q&A community policy, "The question author cannot accept their own answer. They can only accept answers by others"

I’m reposting your solution here so you can mark it as accepted if it resolves your query

Resolution: The root cause of the issue was the default timeout of the HttpClient instance in your .NET Function App A. By default, an HttpClient request will time out after 100 seconds (1 minute and 40 seconds), which precisely matches the behavior you observed. Although your await call was correctly pausing execution, the underlying HTTP task itself was being cancelled by this client-side timeout. By setting the HttpClient.Timeout property to a longer duration (e.g., TimeSpan.FromMinutes(10)), you explicitly instructed the client to wait longer than Function App B's processing time, allowing it to receive the response successfully.

Please don’t forget to Accept Answer and Yes for "was this answer helpful" wherever the information provided helps you, this can be beneficial to other community members.

Share via

Function App not waiting for the response from other function app

1 answer

Your answer