cargo update: Usage, Options & Common CI Errors

Refresh your locked dependency versions.

cargo update recomputes Cargo.lock, moving dependencies to the newest versions allowed by Cargo.toml. It only edits the lockfile; it does not change Cargo.toml requirements.

What it does

Re-resolves the dependency graph against your version requirements and writes the result to Cargo.lock. Without -p it can bump everything; with -p it updates only the named package.

Common usage

cargo update                          # update all deps in the lock
cargo update -p serde                  # update just serde
cargo update -p serde --precise 1.0.200
cargo update --dry-run                 # show what would change

Common CI error: silently bumped versions

Running cargo update in CI rewrites Cargo.lock so the build no longer matches what you committed, hiding breakage and defeating reproducibility. Fix: never run a bare cargo update in CI - use cargo build --locked instead, and run cargo update intentionally in a dependency-bump PR.

Options

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