Fixed: dotnet - An error occurred while loading required library libhostpolicy.dylib on macOS

Having manually upgraded the .net SDK to the latest sercurity patch (8.0.10 at the time) by downloading dotnet-sdk-8.0.403-osx-arm64.tar.gz, verifying the SHA (with shasum -a 512 {file.tar.gz}) and installing it with:

tar -xf ~/Downloads/dotnet-sdk-8.0.403-osx-arm64.tar.gz -C $DOTNET_HOME

dotnet --version

I was then presented with the following error:

Failed to load /Users/andrew/.dotnet/shared/Microsoft.NETCore.App/8.0.10/libhostpolicy.dylib, error: dlopen(/Users/andrew/.dotnet/shared/Microsoft.NETCore.App/8.0.10/libhostpolicy.dylib, 0x0001): tried: ‘/Users/andrew/.dotnet/shared/Microsoft.NETCore.App/8.0.10/libhostpolicy.dylib’ (code signature in <01304A40-8F81-33A7-A0B6-8A333DC79FC2> ‘/Users/andrew/.dotnet/shared/Microsoft.NETCore.App/8.0.10/libhostpolicy.dylib’ not valid for use in process: library load disallowed by system policy), ‘/System/Volumes/Preboot/Cryptexes/OS/Users/andrew/.dotnet/shared/Microsoft.NETCore.App/8.0.10/libhostpolicy.dylib’ (no such file), ‘/Users/andrew/.dotnet/shared/Microsoft.NETCore.App/8.0.10/libhostpolicy.dylib’ (code signature in <01304A40-8F81-33A7-A0B6-8A333DC79FC2> ‘/Users/andrew/.dotnet/shared/Microsoft.NETCore.App/8.0.10/libhostpolicy.dylib’ not valid for use in process: library load disallowed by system policy) An error occurred while loading required library libhostpolicy.dylib from [/Users/andrew/.dotnet/shared/Microsoft.NETCore.App/8.0.10]

The key part of this error message is: library load disallowed by system policy - turns out that the protections in macOS mean, ironically, this security patch is flagged as insecure and quarantined.

The fix is simple:

cd $DOTNET_HOME

xattr -d -r com.apple.quarantine .