Error 500 on a POST request from a static web app to a web service

LUPO DANIELE 1

Hi community,
I have a problem with a POST request sent to my Azure app service from a static web app. The front end is written in Vue.js, the back end in Python.
When I send this request, the response is an Internal Server Error(error 500). In the app log I can see there's a HttpRequestException.
Have you got any ideas on how to solve?
N.B. The app works well in local environment.

Takahito Iwasa 4,851 Reputation points MVP

2023-01-04T00:48:33.803+00:00
Hi, @LUPO DANIELE

Let me sort out your configuration :)

1) Is 172.16.2.3:8000 your Azure App Service? Do you have another private API?

2) What is this error log? This looks like .NET logging output. Do you have a Python error log?
VenkateshDodda-MSFT 23,596 Reputation points Microsoft Employee

2023-01-04T06:19:02.17+00:00
@LUPO DANIELE Thank you for reaching out to Microsoft Q&A, apologize for any inconvenience caused on this.

Based on the shared information from the screenshot, I have looked at the webapp logs in the backend below are the couple of observations:

I can see that your web app is hosted on Free tier app service plan which is a shared plan accessed by across multiple customers.

We see there is high CPU usage and memory usage on the app service backend instance as well.

I would suggest you to scale up your app service plan from free tier to dedicated plans (like Basic, standard, premium) and check whether if you still face the issue.

Posting scaling the app service plan to next tier if you still face the issue, I suggest you run the WebApp Down detector under Diagnose and solve problems of your webapp from the portal to identify the case.

Feel free to reach back to me if you have any further questions on this.

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LUPO DANIELE 1 Reputation point

2023-01-04T11:47:58.527+00:00

I've tried to do what you suggest but still no results. In the portal the following is the only thing that appears

EDIT: I solved the problem by customizing the startup commands of gunicorn. The app was not correctly binded
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VenkateshDodda-MSFT 23,596 Reputation points Microsoft Employee

2023-01-05T05:10:55.967+00:00

@LUPO DANIELE Thanks for sharing the solution I have converted your comment to answer to benefit of other community members.

Lex Li (Microsoft) 5,827 Reputation points Microsoft Employee

2023-01-05T08:09:20.817+00:00

To explain everything you observed further,

The HttpRequestException was from YARP (a .NET based reverse proxy), now widely used inside Azure to forward traffic.

You saw this exception because YARP received your HTTP POST request from vue.js and tried to forward it to the Python backend.

"Failed to forward request" is a good indicator that your Python backend was not up properly.

Luckily you found out that gunicorn was not configured correctly, so everything matched.
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Error 500 on a POST request from a static web app to a web service

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