Sentry + OpenTelemetry Issue Reproduction

Issue: Sentry SDK interferes with OpenTelemetry fetch spans in Node.js even with skipOpenTelemetrySetup: true

Problem Description

When initializing Sentry SDK alongside OpenTelemetry instrumentation, Nextjs fetch spans stop being generated, despite:

• Setting skipOpenTelemetrySetup: true in Sentry configuration
• Properly configuring OpenTelemetry auto-instrumentations
• Loading OpenTelemetry before Sentry initialization

Environment

• Node.js: v22.17.1
• Next.js: 15.5.2
• @sentry/nextjs: ^10.11.0
• @opentelemetry/auto-instrumentations-node: ^0.63.0
• OS: macOS Darwin 24.6.0

Reproduction Steps

Prerequisites

1. Clone this repository

2. Install dependencies:

   npm install

3. Start the local observability stack (OpenTelemetry Collector + Tempo + Grafana):

   npm run observability:up

   This will start:

   • OpenTelemetry Collector (ports 4317/4318)
   • Tempo (trace storage)
   • Grafana (http://localhost:3003)

   Note: First login to Grafana requires username: admin and password: admin

Test Case 1: Without Sentry (✅ Expected behavior)

1. Ensure SENTRY_DSN is not set in .env
2. Start the server:

   npm run dev

3. Open http://localhost:3000
4. Check traces in Grafana at http://localhost:3003/explore (tempo as source). Pre-configured url for traces search.
5. Result: OpenTelemetry spans are generated and visible grafana. Fetch spans are present.

Test Case 2: With Sentry (❌ Broken behavior)

1. Set SENTRY_DSN in .env file:

   SENTRY_DSN=your-sentry-dsn-here
   

2. Restart the server:

   npm run dev

3. Click "Make Fetch Request" button
4. Check traces in Grafana at http://localhost:3003/explore (tempo as source). Pre-configured url for traces search.
5. Result: OpenTelemetry spans are generated and visible grafana. Fetch spans are not present.

Configuration Details

OpenTelemetry Setup (instrumentation.node.ts)

• Uses @opentelemetry/auto-instrumentations-node with HTTP instrumentation enabled
• Properly configured before Sentry initialization

Sentry Configuration (sentry.server.config.ts)

Sentry.init({
  dsn: process.env.SENTRY_DSN,
  skipOpenTelemetrySetup: true, // Should prevent interference
  integrations: [Sentry.httpIntegration({spans: false})],
});

Load Order

1. OpenTelemetry SDK initializes first (instrumentation.node.ts)
2. Sentry initializes conditionally based on SENTRY_DSN environment variable

Expected Behavior

OpenTelemetry Nextjs fetch instrumentation should continue generating spans when Sentry is enabled with skipOpenTelemetrySetup: true.

Actual Behavior

Fetch spans disappear completely when Sentry SDK is initialized, regardless of the skipOpenTelemetrySetup setting.

Package Dependencies

{
  "@opentelemetry/api": "^1.9.0",
  "@opentelemetry/auto-instrumentations-node": "^0.63.0",
  "@opentelemetry/context-async-hooks": "^2.1.0",
  "@opentelemetry/exporter-trace-otlp-grpc": "^0.204.0",
  "@opentelemetry/sdk-node": "^0.204.0",
  "@sentry/nextjs": "^10.11.0",
  "next": "15.5.2"
}

Observability Stack

Cleanup

To stop the observability stack:

npm run observability:down

Trace Visualization

After running tests, view traces in Grafana:

• Basic exploration: http://localhost:3003/explore
• Pre-configured trace search: url

---

This minimal reproduction case demonstrates the conflict between Sentry and OpenTelemetry instrumentation that prevents proper observability setup.