What causes "failed to compute critical path: %w" in jaegertracing/jaeger?

Inspect the wrapped cause to see which span/timing was rejected.

failed to compute critical path

Error message

failed to compute critical path: %w

What it means

After successfully fetching the trace, the handler calls criticalpath.ComputeCriticalPathFromTraces; if that computation fails it wraps the error as "failed to compute critical path: <cause>". It separates analysis failures from fetch failures so callers know the trace existed but the critical path algorithm could not process it.

Solutions

Inspect the wrapped cause to see which span/timing was rejected.
Try a different, known-good trace ID to confirm the algorithm works and the issue is trace-specific data.
Check the ingestion path that produced the trace for instrumentation bugs (invalid timestamps/durations).
If reproducible on valid traces, report it with the trace ID and Jaeger version.

Defensive patterns

Strategy: fallback

Try / catch

out, err := handler.Handle(ctx, input)
if err != nil && strings.Contains(err.Error(), "failed to compute critical path:") {
    // trace fetched OK but analysis failed; fall back to returning the raw trace/span list
    return fetchRawTrace(ctx, input.TraceID)
}

Prevention

Validate trace integrity at ingestion (valid timestamps, durations, parent references).
Test critical-path computation against traces from each instrumented service.
Offer a raw-trace fallback path when analysis fails.

When it happens

Trigger: ComputeCriticalPathFromTraces returns an error on a retrieved trace — typically malformed or inconsistent span data (missing/unparseable timings, malformed references) retrieved by handle().

Common situations: Traces ingested by older/buggy instrumenters producing spans with invalid durations or parent references; corruption from a storage migration; traces with zero spans passing edge cases in the algorithm.

Related errors

AI-assisted analysis of jaegertracing/jaeger@806f444784 (2026-09-01). Data as JSON: /api/errors/8003cf40c5871bee. Report an issue: GitHub.

Appendix: source

Thrown at cmd/jaeger/internal/extension/jaegerquery/internal/mcptools/internal/handlers/get_critical_path.go:81

	for t, err := range aggregatedIter {
		if err != nil {
			return nil, types.GetCriticalPathOutput{}, fmt.Errorf("failed to get trace: %w", err)
		}

		traceFound = true
		trace = t
		break // We expect only one trace since we're querying by a single trace ID
	}

	if !traceFound {
		return nil, types.GetCriticalPathOutput{}, errors.New("trace not found")
	}

	// Compute critical path
	criticalPathSections, err := criticalpath.ComputeCriticalPathFromTraces(trace)
	if err != nil {
		return nil, types.GetCriticalPathOutput{}, fmt.Errorf("failed to compute critical path: %w", err)
	}

	// Build output
	output := h.buildOutput(input.TraceID, trace, criticalPathSections)

	return nil, output, nil
}

// buildQuery converts GetCriticalPathInput to querysvc.GetTraceParams.
func (*getCriticalPathHandler) buildQuery(input types.GetCriticalPathInput) (querysvc.GetTraceParams, error) {
	// Validate input
	if input.TraceID == "" {
		return querysvc.GetTraceParams{}, errors.New("trace_id is required")
	}

	traceID, err := parseTraceID(input.TraceID)
	if err != nil {
		return querysvc.GetTraceParams{}, fmt.Errorf("invalid trace_id: %w", err)

View on GitHub (pinned to 806f444784)