In our projects, we use Hyper version 0.10 because from 0.11 onwards is started using tokio which blew up the dependency tree. We also use Rust v1.24 (the newest version available on Debian) and the newest Hyper version doesn't support that Rust version anymore.

Hyper v0.10 has a dependency on base64 v0.9.

Note that in base64 v0.9.0, safemem 0.2 is used which is compatible with Rust v1.24. However, in base64 v0.9.3, the safemem dependency is bumped to the new major version 0.3 without bumping the base64 major version.

Since safemem 0.3 released an update 2 weeks ago that breaks with Rust v1.24, the result is that Hyper v0.10.19 is no longer compatible with Rust v1.24 (and this with Debian).

I don't like to fingerpoint, but I would just want to encourage the maintainers of this library to be cautious with dependency management. Especially for a crate as trivial as base64, extreme care should be applied when bumping dependencies.

The result in this case is that it's no longer possible to use Hyper without tokio on Debian.