Raspberry Pi install netcore3.1

Checked the information. Except that a specific version of ubuntu supports arm64, the other default versions only support arm32.
However, arm32 does not have a package management tool to install. You need to manually install it. Then gossip and start.

Manual installation guide
https://docs.microsoft.com/zh-cn/dotnet/core/install/sdk?pivots=os-linux#download-and-manually-install

file download address, be sure to select linux-arm32
https : //dotnet.microsoft.com/download/dotnet-core/3.1

wget  https://download.visualstudio.microsoft.com/download/pr/ccbcbf70-9911-40b1-a8cf-e018a13e720e/03c0621c6510f9c6f4cca6951f2cc1a4/dotnet-sdk-3.1 .201-linux-arm.tar.gz

mkdir -p $HOME/dotnet && tar zxf dotnet-sdk-3.1.100-linux-x64.tar.gz -C $HOME/dotnet

export DOTNET_ROOT=$HOME/dotnet

export PATH = $ PATH: $ HOME / dotnet

This is fine , test it