# Run-time configuration options for networking

## HTTP/2 protocol

• Configures whether support for the HTTP/2 protocol is enabled.

• Introduced in .NET Core 3.0.

• .NET Core 3.0 only: If you omit this setting, support for the HTTP/2 protocol is disabled. This is equivalent to setting the value to false.

• .NET Core 3.1 and .NET 5+: If you omit this setting, support for the HTTP/2 protocol is enabled. This is equivalent to setting the value to true.

Setting name Values
runtimeconfig.json System.Net.Http.SocketsHttpHandler.Http2Support false - disabled
true - enabled
Environment variable DOTNET_SYSTEM_NET_HTTP_SOCKETSHTTPHANDLER_HTTP2SUPPORT 0 - disabled
1 - enabled

## UseSocketsHttpHandler

Setting name Values
runtimeconfig.json System.Net.Http.UseSocketsHttpHandler true - enables the use of SocketsHttpHandler
false - enables the use of WinHttpHandler on Windows or libcurl on Linux
Environment variable DOTNET_SYSTEM_NET_HTTP_USESOCKETSHTTPHANDLER 1 - enables the use of SocketsHttpHandler
0 - enables the use of WinHttpHandler on Windows or libcurl on Linux

Note

Starting in .NET 5, the System.Net.Http.UseSocketsHttpHandler setting is no longer available.

## Latin1 headers (.NET Core 3.1 only)

• This switch allows relaxing the HTTP header validation, enabling SocketsHttpHandler to send ISO-8859-1 (Latin-1) encoded characters in headers.

• If you omit this setting, an attempt to send a non-ASCII character will result in HttpRequestException. This is equivalent to setting the value to false.

Setting name Values
runtimeconfig.json System.Net.Http.SocketsHttpHandler.AllowLatin1Headers false - disabled
true - enabled
Environment variable DOTNET_SYSTEM_NET_HTTP_SOCKETSHTTPHANDLER_ALLOWLATIN1HEADERS 0 - disabled
1 - enabled

Note

This option is only available in .NET Core 3.1 since version 3.1.9, and not in previous or later versions. In .NET 5 we recommend using RequestHeaderEncodingSelector.