413 content to large for .net core

Question

413 content to large for .net core

Paras Panchal 20

I have an API endpoint that accepts a multipart/form-data request containing 10 files along with some additional form fields. This works perfectly in my local development environment where I’ve configured Kestrel to allow unlimited request body size (MaxRequestBodySize = null).

However, when deployed to IIS, I encounter a 413 Payload Too Large error. I’m aware that I can increase the request size limit in the IIS settings (e.g., maxAllowedContentLength, maxRequestLength), but I would prefer not to change the global settings since that could affect other endpoints and introduce potential risks.

Is there a way to configure IIS or the .NET Core application to allow larger request sizes only for this specific endpoint without impacting others?

Any guidance or best practices would be greatly appreciated.

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Answer 1

SurferOnWww 4,391

Is there a way to configure IIS or the .NET Core application to allow larger request sizes only for this specific endpoint without impacting others?

If you deployed your ASP.NET Core app to IIS properly, the web.config was automatically generated and included under the site root as shown below;

enter image description here

The code of web.config is something like below:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <location path="." inheritInChildApplications="false">
    <system.webServer>
      <handlers>
        <add name="aspNetCore" path="*" verb="*" 
          modules="AspNetCoreModuleV2" 
          resourceType="Unspecified" />
      </handlers>
      <aspNetCore processPath="dotnet" 
        arguments=".\CookieSample.dll" stdoutLogEnabled="false" 
        stdoutLogFile=".\logs\stdout" hostingModel="inprocess" />
    </system.webServer>
  </location>
</configuration>
<!--ProjectGuid: 8F4EB672-B56E-4BC4-9909-A9EE199CDE1D-->

You can set the maxAllowedContentLength in the web.config above without impacting the other sites than the above site.

Paras Panchal 20 Reputation points

2025-04-25T05:15:54.44+00:00

Sir, currently there are multiple endpoints under the same API. I understand that we can configure maxAllowedContentLength, but after discussing with my team, there's some concern that modifying this setting might impact other endpoints. I'm wondering if there's a way to handle this configuration specifically for a particular endpoint through code. I'm not entirely sure of the best approach here, so any suggestions or guidance from your side would be greatly appreciated.
SurferOnWww 4,391 Reputation points

2025-04-25T06:14:31.2533333+00:00

I have an API endpoint that accepts a multipart/form-data request containing 10 files along with some additional form fields. there's some concern that modifying this setting might impact other endpoints.

Do you mean that there are the "other endpoints" (such as action methods to handle CRUD operation of DB or something) under the site in addition to the "API endpoint that accepts a multipart/form-data request containing 10 files along with some additional form fields" and want to apply the maxAllowedContentLength only to the "API endpoint"?

Sorry, I have no idea to apply the maxAllowedContentLength only to "an API endpoint."

Answer 2

Bruce (SqlWork.com) 75,051

you would update the IIS setting in the web.config of the site, so it only applies to the desired site.

note: be sure the desired settings are not locked down in the IIS global configs.

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413 content to large for .net core

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