Chainstack Ethereum newHeads Visibility Loss Across European Probes
During Chainstack's public London cluster incident on May 22, 2026, QuantLoop observed a live block visibility loss: Chainstack's Ethereum newHeads websocket stream stopped delivering new block headers to probes in London, Frankfurt, and Amsterdam.
Summary
On May 22, 2026, QuantLoop observed Chainstack's Ethereum newHeads websocket stream stop delivering new block headers to its London, Frankfurt, and Amsterdam probes. Chainstack later reported a partial outage affecting its London cluster.
QuantLoop classifies this as a provider-scoped block visibility incident. The observed failure mode was a loss of live Ethereum head delivery from Chainstack to the affected probes.
The regional pattern is consistent with routing or shared dependency on Chainstack's London cluster, but it does not prove where Chainstack physically runs Ethereum nodes.
During the visibility gap, the affected probes did not observe 168 Ethereum blocks in real time: blocks 25,148,191 through 25,148,358. Header delivery resumed at block 25,148,359.
Timeline
Times are shown in UTC. Chainstack's public incident timeline is included for context alongside QuantLoop's observed visibility loss.
- 2026-05-22 03:45:50ZQuantLoop detects newHeads visibility loss across LHR, FRA, and AMSQuantLoop's London, Frankfurt, and Amsterdam probes stopped receiving new Ethereum block headers from Chainstack's websocket
newHeadsstream. - 2026-05-22 04:01:00ZChainstack begins investigating London cluster incidentChainstack reported that it was investigating a partial outage in its London cluster.
- 2026-05-22 04:18:48ZQuantLoop probes observe Chainstack newHeads recoveryQuantLoop's LHR, FRA, and AMS probes started receiving new Ethereum block headers from Chainstack again.
- 2026-05-22 04:23:00ZChainstack marks incident as identifiedChainstack reported that the issue had been identified and that work on a fix was continuing.
- 2026-05-22 05:11:00ZChainstack reports fix implemented and monitoringChainstack reported that a fix had been implemented and that results were being monitored.
- 2026-05-22 07:15:00ZChainstack marks incident resolvedChainstack marked the London cluster incident as resolved.
Interpretation
This event shows that a websocket can remain connected while no longer delivering new block headers.
For systems that react to new blocks, endpoint reachability is not enough. The endpoint also needs to expose the latest head when the rest of the monitored network sees it.
This is the distinction between RPC latency and block visibility latency: response speed measures how fast an endpoint answers, while visibility measures when new chain state becomes observable. QuantLoop explains this in RPC Latency vs Block Visibility Latency.
The LHR, FRA, and AMS pattern is consistent with regional routing, shared upstream dependencies, or configuration tied to Chainstack's London cluster. It does not prove physical node placement.
External status reference
Chainstack publicly reported a partial outage in its London cluster on May 22, 2026. QuantLoop's observations were collected independently from its Ethereum probes.
View Chainstack status page