lockfile generation would downgrade recorded provenance…

Error message

lockfile generation would downgrade recorded provenance; previous files were preserved

What it means

mise's lockfile records cryptographic provenance (e.g. SLSA attestations) for each locked artifact. During `lockfile generate`, `ensure_no_downgrade` compares the existing recorded provenance with the newly computed one; if the new provenance is weaker or absent (including the packslip-signer-replaces-provenance case), generation aborts so previously written lockfiles are preserved untouched. This is a trust-safety guard, not a bug.

Solutions

Check why the new provenance is weaker: verify the packslip manifest/attestations are still published for the target version
Re-enable attestation settings (e.g. `github_attestations`) that were disabled in settings.toml
Regenerate with the backend that produced the original provenance (e.g. packslip:) instead of a fallback backend
If the downgrade is intentional, delete/review the existing lockfile entry first so generation starts from a clean trusted state

Example fix

# before: attestations disabled, regeneration downgrades provenance
[settings.ruby]
github_attestations = false
# after
[settings.ruby]
github_attestations = true

Defensive patterns

Strategy: validation

Validate before calling

let old = existing_entry.provenance.as_ref();
let new = computed_entry.provenance.as_ref();
if new.is_none() || new.map(|n| n.kind()) != old.map(|o| o.kind()) {
    // provenance would be downgraded — regenerate with attesting backend first
}

Prevention

Keep attestation settings (github_attestations) enabled consistently across environments
Always regenerate lockfiles with the same backend that produced the original provenance
Don't disable attestations in CI before regenerating lockfiles
Review lockfile provenance fields after backend or registry changes

When it happens

Trigger: Running lockfile generation (`mise lock` / internal `generate`) for a tool whose existing lockfile entry has provenance (or a packslip signer) recorded, but the regenerated entry's provenance is missing or weaker per `provenance_is_downgrade` — e.g. the backend stopped serving attestations, the packslip manifest no longer includes them, or settings for attestations were disabled.

Common situations: Regenerating a lockfile after a registry/backend change dropped attestation data; switching a backend from packslip to a non-attesting backend; CI regenerating lockfiles after attestations were temporarily unavailable upstream; toggling `github_attestations` settings off.

Understand the failure class

Background: Checksum mismatch errors: "checksum verification failed", "digest mismatch", "expected vs actual checksum" — what they mean and how to fix them — this error's family across 41 libraries.

Related errors

AI-assisted analysis of jdx/mise@533346cc37 (2026-09-17). Data as JSON: /api/errors/7e80a9afb266cd73. Report an issue: GitHub.

Appendix: source

Thrown at src/lockfile/generate.rs:783

        lockfile.set_uv_lock(&ba.short, &tv.version, &backend_name, &options, graph)?;
    }
    Ok(())
}

fn ensure_no_downgrade(old: &PlatformInfo, new: &PlatformInfo, backend: &str) -> Result<()> {
    // A verified Packslip signer is the replacement trust baseline for an
    // artifact authenticated by its signed release manifest. Older incremental
    // lock updates could carry detected GitHub provenance into a Packslip entry,
    // but complete generation intentionally does not persist that unverified
    // link. Without a signer, retain the ordinary provenance ratchet.
    let packslip_signer_replaces_provenance =
        backend.starts_with("packslip:") && new.signer.is_some();
    if provenance_is_downgrade(
        old.provenance.as_ref(),
        new.provenance.as_ref(),
        packslip_signer_replaces_provenance,
    ) {
        bail!(
            "lockfile generation would downgrade recorded provenance; previous files were preserved"
        );
    }
    if let Some(signer) = &old.signer
        && (new.signer.as_ref() != Some(signer) || new.attested_by != old.attested_by)
    {
        bail!(
            "lockfile generation would change the recorded signer; previous files were preserved"
        );
    }
    // Preserve identities across reordering, then pair replaced URLs in their
    // configured order so version upgrades retain the previous trust baseline.
    let mut replacements = new.additional_artifacts.iter().filter(|artifact| {
        !old.additional_artifacts
            .iter()
            .any(|old| old.url == artifact.url)
    });
    for artifact in &old.additional_artifacts {

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