Notes from a 2 AM On-Call: browser-use Agent Silently Dropping Sessions Under Concurrent Load

The Failure Symptom

[2025-01-18 02:17:33] ERROR: Agent task timeout after 30s [2025-01-18 02:17:33] WARNING: Browser session closed unexpectedly [2025-01-18 02:18:01] ERROR: Agent task timeout after 30s [2025-01-18 02:18:01] WARNING: Browser session closed unexpectedly

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Production FastAPI service integrating browser-use for automated data extraction. Single-threaded workers handling 8-12 concurrent agent requests. No crash logs, no exceptions—just silent timeouts and "session closed" warnings. Resource usage looked normal: CPU at 40%, memory stable.

The failure pattern was insidious: first 3-4 requests succeeded, then everything after request 5 started timing out.…