We’re seeing new Workflow runs fail during startup with workflow@4.2.4. The SDK throws a schema validation error while posting to /v3/runs/{runId}/events.
Error shape:
WorkflowWorldError: Schema validation failed for POST /v3/runs/{runId}/events:
run.output: Invalid input: expected nonoptional, received undefined
run.error: Invalid input: expected nonoptional, received undefined
run.completedAt: Invalid input: expected nonoptional, received undefined
This began suddenly. The same app path was successfully creating Workflow run ids earlier the same day, then later started failing with the schema error above. Application code around the Workflow start call
did not change between those tests.
Current package:
workflow: 4.2.4
next: 16.2.6
The failure happens at Workflow startup, before the app can use the returned run id. It looks like the Workflow backend is returning a run object where output, error, and completedAt are omitted, while the SDK schema expects those fields to exist, likely as null for a new/running run.
Question: was there a Workflows backend response-shape change around May 14, 2026 that could make workflow@4.2.4 reject newly-created run event payloads?