Failed to read the request form. Request body too large. The max request body size is 30000000 bytes

[Nefcanto]

We're stuck on making .NET accept big file uploads.

We develop on Linux, deploy inside containers, and run behind Nginx reverse proxy.

We develop using dotnet build and dotnet bin/Project.dll, and we deploy using dotnet publish -o /path and run inside a docker container using dotnet Project.dll.

In the development environment we do not have a web.config file, but when we use the publish command, it creates a default web.config file for us.

We have already added these lines to our Startup.cs file:

services.Configure<FormOptions>(x =>
{
    x.ValueLengthLimit = int.MaxValue;
    x.MultipartBodyLengthLimit = int.MaxValue;
    x.MultipartHeadersLengthLimit = int.MaxValue;
});

But it seems that this is not enough. In our development environment, we do not have a web.config file so we can't configure our API using that. We tried to configure Kestrel using this code:

services.Configure<Microsoft.AspNetCore.Server.Kestrel.KestrelServerOptions>(options =>
{
    options.Limits.MaxRequestBodySize = int.MaxValue;
});

But we got this error:

error CS0234: The type or namespace name 'KestrelServerOptions' does not exist in the namespace 'Microsoft.AspNetCore.Server.Kestrel' (are you missing an assembly reference?)

We can use per action configuration as follow, and it works.

[RequestFormLimits(ValueLengthLimit = int.MaxValue,
        MultipartBodyLengthLimit = long.MaxValue)]
[DisableRequestSizeLimit]

But we want to enable large file upload for all of our APIs.

How should we do it?

[david-acker]

Could you try configuring Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServerOptions instead?

API Docs: KestrelServerOptions

It looks like KestrelServerOptions actually used be in the Microsoft.AspNetCore.Server.Kestrel namespace back in ASP.NET Core 1.1, but has since been moved to Microsoft.AspNetCore.Server.Kestrel.Core. That old version of the docs is the first search result I'm getting for "KestrelServerOptions" on Google, which is a bit confusing.

[Nefcanto]

@david-acker thank you. That solved it. I didn't check the version of KestrelServerOptions.

[davidfowl]

All of the information with code samples are on this page: https://learn.microsoft.com/en-us/aspnet/core/mvc/models/file-uploads?view=aspnetcore-7.0

Here's how you tweak the limit in Kestrel:

https://learn.microsoft.com/en-us/aspnet/core/mvc/models/file-uploads?view=aspnetcore-7.0#kestrel-maximum-request-body-size

It's not showing the WebApplicationBuilder pattern:

builder.WebHost.ConfigureKestrel(options =>
{
    options.Limits.MaxRequestBodySize = A big number; // Maybe avoid int.MaxValue
});