BerriAI/litellm · error · HTTPException

Concurrent write conflict — please retry

Error message

Concurrent write conflict — please retry

What it means

HTTPException(409) raised after a sequence-number UniqueViolationError persisted through all retry attempts while appending a workflow event inside the transaction: concurrent writers kept claiming the same next sequence_number. It signals a lost race — the client should retry the append.

Source

Thrown at litellm/proxy/management_endpoints/workflow_management_endpoints.py:408

            async with prisma_client.db.tx() as tx:
                event: object = await tx.litellm_workflowevent.create(data=event_data)
                if new_status:
                    await tx.litellm_workflowrun.update(
                        where={"run_id": run_id},
                        data={"status": new_status},
                    )

            return event

        except Exception as e:
            if UniqueViolationError is not None and isinstance(e, UniqueViolationError):
                if attempt == _MAX_SEQUENCE_RETRIES - 1:
                    verbose_proxy_logger.exception(
                        "Sequence number collision after %d retries for run %s",
                        _MAX_SEQUENCE_RETRIES,
                        run_id,
                    )
                    raise HTTPException(
                        status_code=409,
                        detail="Concurrent write conflict — please retry",
                    )
                continue
            verbose_proxy_logger.exception("Error appending workflow event: %s", e)
            raise HTTPException(status_code=500, detail=str(e))

    raise HTTPException(status_code=500, detail="Failed to append event")  # pragma: no cover


@router.get(
    "/v1/workflows/runs/{run_id}/events",
    tags=["workflow management"],
    dependencies=[Depends(user_api_key_auth)],
)
async def list_workflow_events(
    run_id: str,
    limit: int = Query(100, ge=1, le=500),

View on GitHub (pinned to 77b7c6c40c)

Solutions

1. Retry the request; the conflict is transient.

When it happens

Trigger: Thrown at litellm/proxy/management_endpoints/workflow_management_endpoints.py:408 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of BerriAI/litellm@77b7c6c40c (2026-08-18). Data as JSON: /api/errors/c9ae7c9835eb9eae. Report an issue: GitHub.