Mongoose: Operation buffering timed out after 10000ms
MongooseError: Operation `users.findOne()` buffering timed out after 10000ms
at Timeout._onTimeout (node_modules/mongoose/lib/drivers/node-mongodb-native/collection.js:187:23)
at listOnTimeout (node:internal/timers:557:17)
Immediate Remediation
bash
Ensure MongoDB is reachable and call mongoose.connect() before any model operation; set mongoose.set('bufferCommands', false) to fail fast during startup.Root Cause Analysis
Mongoose buffers model operations when the connection is not yet established, and if the MongoDB server does not respond within the 10-second buffer timeout, the operation fails. This usually happens because mongoose.connect() was never called, the connection string is wrong, or the database is down/unreachable.
Verification & Guardrails
- Verify the MongoDB URI and network connectivity with `mongosh --eval "db.runCommand({ping:1})"` before blaming the app.
- In production, set serverSelectionTimeoutMS in the connection options to control how long the driver waits for a server.
- If using Mongoose 6+, the default bufferTimeoutMS is 10000; you can adjust it with mongoose.set('bufferTimeoutMS', 30000) but prefer fixing the connection.
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