expected events [%v-%v] but got events [%v-%v] of length %v:

Error message

expected events [%v-%v] but got events [%v-%v] of length %v: isFirstPage=%v,isLastPage=%v,pageSize=%v

What it means

Error "expected events [%v-%v] but got events [%v-%v] of length %v: isFirstPage=%v,isLastPage=%v,pageSize=%v" thrown in temporalio/temporal.

Source

Thrown at service/history/api/get_history_util.go:505

	}

	if !isLastPage {
		// estimate lastEventID based on pageSize. This is a lower bound
		// since the persistence layer counts "batch of events" as a single page
		expectedLastEventID = expectedFirstEventID + int64(pageSize) - 1
	}

	nExpectedEvents := expectedLastEventID - expectedFirstEventID + 1

	if firstEvent.GetEventId() == expectedFirstEventID &&
		((isLastPage && lastEvent.GetEventId() == expectedLastEventID && int64(eventCount) == nExpectedEvents) ||
			(!isLastPage && lastEvent.GetEventId() >= expectedLastEventID && int64(eventCount) >= nExpectedEvents)) {
		return nil
	}

	return softassert.UnexpectedDataLoss(logger,
		"Incomplete history",
		fmt.Errorf("expected events [%v-%v] but got events [%v-%v] of length %v: isFirstPage=%v,isLastPage=%v,pageSize=%v",
			expectedFirstEventID,
			expectedLastEventID,
			firstEvent.GetEventId(),
			lastEvent.GetEventId(),
			eventCount,
			isFirstPage,
			isLastPage,
			pageSize))
}

// ProcessInternalRawHistory processes history in the field response.History.
// History service can send history events in response.History.Events. In that case, process the events and move them
// to response.Response.History. Usually this is done by history service but when history.sendRawHistoryBetweenInternalServices
// is enabled, history service sends raw history events to frontend without any processing.
func ProcessInternalRawHistory(
	requestContext context.Context,
	saProvider searchattribute.Provider,
	saMapperProvider searchattribute.MapperProvider,

View on GitHub (pinned to bde624efd1)

When it happens

Trigger: Thrown at service/history/api/get_history_util.go:505 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of temporalio/temporal@bde624efd1 (2026-09-01). Data as JSON: /api/errors/8855c051f225ba50. Report an issue: GitHub.