[GitLab 19.0.2] setBranchStatus crashes (TypeError: err.body.message.startsWith) → all PR creation stalls

[mean2k]

How are you running Renovate?

Self-hosted Renovate CLI

Which platform you running Renovate on?

GitLab (.com or self-hosted)

Which version of Renovate are you using?

43.242.0

Please tell us more about your question or problem

Describe the proposed change(s) / bug
On self-hosted Renovate against GitLab CE 19.0.2, every repo run aborts each branch during status-check setting:

WARN: Error updating branch (branch=renovate/...)
TypeError: err.body?.message?.startsWith is not a function
at Proxy.setBranchStatus (lib/modules/platform/gitlab/index.ts:1047:26)
at setStatusCheck (lib/workers/repository/update/branch/status-checks.ts:56:5)
at setStability (lib/workers/repository/update/branch/status-checks.ts:109:3)
at setBranchStatusChecks (lib/workers/repository/update/branch/index.ts:64:3)

It throws while setting the internal renovate/stability-days commit status — before PR creation — so no MRs are created at all. Extraction completes (result: "done"), but zero branches/PRs progress: a silent, instance-wide stall.

Environment

• Renovate 43.242.0 (self-hosted renovate/renovate Docker) — also on 43.234.0
• Platform GitLab CE 19.0.2 (started immediately after upgrading 19.0.1 → 19.0.2)
• Config with minimumReleaseAge/stabilityDays + internalChecksFilter: "strict"

Root cause
The error guard at gitlab/index.ts:~1047 calls err.body?.message?.startsWith('Cannot transition...') assuming message is a string. GitLab 19.0.2 returns an error on the commit-status POST whose body.message is non-string (GitLab emits ActiveRecord validation errors as {"message": {...}}), so .startsWith throws.
Independently verified: a fresh POST /statuses/:sha succeeds; transition errors (running→running) return string messages ("Cannot transition status via :run from :running") which the guard handles. The crashing path is a different error with a non-string message.

Suggested fix — type-guard before .startsWith:
const msg = err.body?.message;
if (typeof msg === 'string' && msg.startsWith('Cannot transition status')) { /* ignore */ }

Workaround (confirmed): remove stabilityDays/minimumReleaseAge → no renovate/stability-days status → no setBranchStatus call → PRs flow again.

Note on reproduction: couldn't capture the raw err.body after the fact — the TypeError replaces it in logs and the affected branches have since merged (workaround live). The fix is a defensive type-guard, independent of the exact body.

Logs (if relevant)

Logs

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