Elevate ASP.NET Core file upload size limit

In ASP.NET Core, you may encounter file upload size limits. To resolve this issue, you need to consider the restrictions imposed by both the Web Server (IIS) and the ASP.NET Core Server (Kestrel).

IIS file size limit

As mentioned in the link resource you provide, IIS has default limits on file upload size. To increase this limit for your application, follow these steps:

1. Open IIS Manager.
2. Navigate to the application pool used by your website.
3. Right-click and select Properties.
4. On the Limits tab, increase the value of "Maximum Allowed Content Length".

Kestrel file size limit

Since ASP.NET Core 2.0, Kestrel has also imposed its own restrictions on file uploads. These limitations are defined in the KestrelServerLimits.cs file.

To increase the file size limit in Kestrel, you can use the following methods:

MVC operation method

Use the [RequestSizeLimit] feature on a specific MVC operation method or controller to override the default limit. For example:

[HttpPost]
[RequestSizeLimit(100_000_000)]
public IActionResult MyAction([FromBody] MyViewModel data)
{
}

General Middleware

Use the IHttpMaxRequestBodySizeFeature feature to modify the limit for each request:

app.Run(async context =>
{
    context.Features.Get().MaxRequestBodySize = 100_000_000;
});

Global configuration

Modify the MaxRequestBodySize property in the callback function of UseKestrel or UseHttpSys to set the limit globally:

.UseKestrel(options =>
{
    options.Limits.MaxRequestBodySize = null; // 无限制
});

.UseHttpSys(options =>
{
    options.MaxRequestBodySize = 100_000_000;
});

Through the above steps, you can increase the file upload size limit for both the web server and the Kestrel server in ASP.NET Core.