Increase Azure App Service HTTP Post Body Length Limit

Donovan Bouton 1

My website, hosted on Azure App Service Plan, will not allow POST requests with a body larger than 100,000 characters.

Locally, the website will allow any limit.

How do I change this setting?

I do not see any Azure Web App Firewall within my App Service Plan or App Service.

SnehaAgrawal-MSFT 18,366 Reputation points

2022-01-13T10:34:47.487+00:00

Thanks for asking question! Could you please elaborate if you are receiving any error when request with a body larger than 100,000 characters? You have hosted the app in which language? Could you share the screen shot to help you better on this.

1 answer

Ravikumar Narayanam 1 Reputation point Microsoft Employee

2022-07-04T08:16:45.777+00:00
Hi , To fix the Issue to allow max character's In the request, you need to make below changes In wwwroot folder.

By default Request Limits value for the maxAllowedContentLength on IIS which is 30000000 (roughly 28.6MB) in Azure web app. To modify this value, add the following to your web.config file. And add this file under wwwroot

Create web.config file in wwwroot folder If not exists and then add the below settings In that config file

<configuration>
<system.webServer>
<security>
<requestFiltering>
<requestLimits maxAllowedContentLength="<valueInBytes>"/>
</requestFiltering>
</security>
</system.webServer>
</configuration>

Mention the value how much you would like to allow in maxAllowedContentLength

Save the changes , restart the Appservice and test the application.

Reference :
https://azureossd.github.io/2016/06/15/uploading-large-files-to-azure-web-apps/index.html
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David Smith 1 Reputation point

2022-09-19T16:52:59.397+00:00

Does Azure use the web.config? I though Azure defaulted to hosting with Kestrel. Kestrel doesn't use web.config, does it?

I have tried this on my .NET CORE 6 App Service running HTTP 2.0 (I read that 2.0 solves the issue - it didn't for me). No luck. I also added attributes to my controller method. These only helped locally, not after deployment to Azure:

[HttpPost]
[RequestSizeLimit(100 * 1024 * 1024)]
[RequestFormLimits(MultipartBodyLengthLimit = 100 * 1024 * 1024)]

I also have this in my program.cs file:

var builder = WebApplication.CreateBuilder(args);
ConfigurationManager configuration = builder.Configuration;
builder.Services.Configure<IISServerOptions>(options => options.MaxRequestBodySize = int.MaxValue);
builder.Services.Configure<FormOptions>(o =>
{
o.ValueLengthLimit = int.MaxValue;
o.MultipartBodyLengthLimit = int.MaxValue;
o.MultipartBoundaryLengthLimit = int.MaxValue;
o.MultipartHeadersCountLimit = int.MaxValue;
o.MultipartHeadersLengthLimit = int.MaxValue;
o.BufferBodyLengthLimit = int.MaxValue;
o.BufferBody = true;
o.ValueCountLimit = int.MaxValue;
});

builder.WebHost.ConfigureKestrel(serverOptions =>
{
serverOptions.Limits.MaxRequestBodySize = 104_857_600;
});

I added these attributes to the App Service configuration:
UPLOAD_MAX_FILESIZE of 128M
POST_MAX_SIZE of 256M

Not sure what else to try. I do not use a proxy or firewall in Azure. My App Service is using a Windows environment, 32-bit, Integrated pipeline and HTTP 2.0 and TLS 1.2.

Any ideas much appreciated!

David Smith 1 Reputation point

2022-09-19T17:02:30.793+00:00

Ah, I see what's going on, now. My above comment prompted me to look directly at the web.config on the server. It does not contain the contents from my project. I likely just need to figure out how to get my project's web.config to merge with the one on the App Service so the following is added:

<configuration>
<system.webServer>
<security>
<requestFiltering>

<requestLimits maxAllowedContentLength="104857600" />
</requestFiltering>
</security>
</system.webServer>
</configuration>

David Smith 1 Reputation point

2022-09-20T20:52:25.807+00:00

Okay, just to be complete, here's what I needed to do to get my DevOps Build and Release Pipeline to transform web.config.

Add a web.Release.config file to my project with the settings above.

Make sure the XML transform checkbox was checked in the DevOps Release configuration. This automatically transforms the final web.config with the web.Release.config modifications.

Engels, Mika 0 Reputation points

2024-04-17T13:56:56.4266667+00:00

Hi, I am currently running into the same issue with my WebApp.
Is there a similar solution for Linux App Services? My App is written with python and flask.
Would be great to have a similar solution. Creating a web.config in the wwwroot directory did not change anything.
Thanks, kind regards!

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