AWS's non_exhaustive Rust Enum Wasn't the Breaking Change. The Type Inside It Was

Tue, 22 Sep 2026 09:00:00 +0530

On September 14, AWS shipped aws-smithy-types 1.7.0, a minor version bump to the low-level crate that every AWS SDK for Rust client depends on. The next day, a user filed smithy-lang/smithy-rs#4853: a clean cargo add aws-config on a fresh project failed to compile, with aws-smithy-json 0.62.4 and 0.63.0 both throwing type errors against the new release. By September 16, AWS had yanked 1.7.0 from crates.io entirely and shipped 1.6.4, restoring the original API.[1][2][3] Two days from breaking release to full revert is fast for a dependency this central, and the postmortem-shaped detail is in the diff: the bug reports all point at one change, #[non_exhaustive], but that wasn’t what broke the build. A second, unrelated change riding in the same release was.

Semver on Kuldeep Pisda

AWS's non_exhaustive Rust Enum Wasn't the Breaking Change. The Type Inside It Was