The 1.99.0 pre-release is ready for testing. The release is scheduled for October 1. Release notes can be found here.
You can try it out locally by running:
RUSTUP_DIST_SERVER=https://dev-static.rust-lang.org rustup update stable
The index is https://dev-static.rust-lang.org/dist/2026-09-28/index.html.
General feedback about our pre-release process is welcome on this GitHub issue.