[Telemetry Data] May 14 ZKSync Sequencer Stall: 5000ms TCP Timeout + Block Production 10x Below Normal (Public Status: Green)

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[Telemetry Data] May 14 ZKSync Sequencer Stall: 5000ms TCP Timeout + Block Production 10x Below Normal (Public Status: Green)

Same monitoring infrastructure that captured the May 13 Arbitrum stall fired twice today on ZKSync Era.

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What Phoenix Zero Recorded

EVENT 1 — 13:57 UTC
🟣 SEQUENCER STALL — ZKSYNC
RTT: 5000ms | P99: 5000ms | P95: 5000ms

EVENT 2 — 14:05 UTC
🟣 SEQUENCER STALL — ZKSYNC
RTT: 5000ms | P99: 5000ms | P95: 5000ms

5000ms = hard socket timeout. The sequencer did not respond to TCP packets within 5 seconds. For an HFT router, this is a black hole: transactions submitted in this window are dropped at the transport layer, never reaching a block.

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On-Chain Verification — Block Production Rate

Normal ZKSync Era block rate: ~2 seconds/block.

Block range	Time span	Rate	vs normal
70098220 → 70098230	13:56:25 → 13:57:01 UTC	3.6s/block	baseline
70098240 → 70098250	13:57:26 → 13:58:17 UTC	5.1s/block	2.5x slower
70098310 → 70098320	14:00:57 → 14:02:10 UTC	7.3s/block	3.6x slower
70098340 → 70098345	14:03:22 → 14:04:13 UTC	10.2s/block	5x slower ← peak

Block production did not stop entirely — but throughput dropped to 1 tx/block (vs normal 2-4) during the stall window. The RPC layer was returning 5000ms timeouts while the sequencer was producing skeleton blocks at severely degraded rate.

Public status pages: no incident reported.

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Concurrent Events (Same Window)

Chain	Time (UTC)	Reading	Type
Optimism	13:54–14:04	P99: 413–574ms sustained	🔵 SLOW CREEP
Base	14:00	P99: 2190ms spike	🔵 SLOW CREEP
ZKSync	13:57, 14:05	RTT: 5000ms	🟣 SEQUENCER STALL

Multi-chain degradation in the same 10-minute window. Base recovered immediately; Optimism sustained degradation for 10 minutes; ZKSync hit the hard timeout ceiling twice.

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Context

ZKSync Era's proof system currently has a documented partial liveness vulnerability (source: L2BEAT). Today's 5000ms TCP timeouts are consistent with this ongoing issue manifesting under load.

The block explorer API itself lags ~2.5 hours behind real-time — meaning on-chain verification of the exact stall window requires waiting for indexing. The RTT sensor fires within 2 seconds of the event.

This is the delta: public infrastructure reports green. Our transport-layer sensor sees the black hole before the block explorer indexes it.

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Infrastructure

Phoenix Zero RTT Oracle probes 4 chains (Base, Arbitrum, Optimism, ZKSync) via eth_blockNumber every 2 seconds.

• WebSocket stream: wss://rtt.phoenix-ai.work/ws
• Live Telegram alerts: @Phoenix_Node_Alex_Bot
• Server: DigitalOcean NYC1 (198.211.103.36)

Previous data point: May 13 Arbitrum stall — 3081ms, 47s delta vs public RPC

Contact: aleksandrkent64@gmail.com