[Rust] Why do I get an invalid toolchain name?

First, check your rustup version using the following commands:

rustup --version

rustup show

Then, find the appropriate remedy:

• Set the minimal rustup profile:

rustup set profile minimal

• Install the nightly Rust toolchain separately with these two commands:

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- --default-toolchain none -y

rustup toolchain install nightly --allow-downgrade --profile minimal --component clippy

• Update rustup with one of these commands:

rustup update

rustup self update

Refer to the Rust toolchain installer for more details.