error[E0658]: non-builtin inner attributes are unstable

Question

I cloned fresh https://github.com/substrate-developer-hub/substrate-node-template repository (sometime ago it was working fine) I have executed:

cargo build --release

and got:

And many, many more errors while compiling. How to cope with that? Any ideas?

Answer 1

I (thanks to Dan) solved it by execution:

rustup update nightly
rustup update stable
// and then
cargo build --release

And works!