{
  "prepared_at_utc": "2026-10-04T00:22:41.038997+00:00",
  "schema_version": 1,
  "scope": "Selected primary-source operational incidents, not an exhaustive outage inventory. Historical census is October 2024 through September 2026; older and newer operational context is explicitly labeled.",
  "method": "Manually reviewed existing evidence and current primary pages. Durations are arithmetic between source-reported timestamps, not independent block/header reconstruction. Full documentation bodies are not retained here.",
  "definitions": {
    "actual_production_halt_seconds": "Nullable. Only populated when the provider explicitly reports a production halt duration/window, or explicitly states production continued. Zero is a statement about this event only, not chain-wide annual uptime.",
    "finality_disruption_seconds": "Nullable. Do not replace unknown with zero or substitute the time an incident ticket was open.",
    "incident_management_window": "Time between report lifecycle timestamps; may include diagnosis, monitoring, recovery lag and periods of normal production.",
    "reporting_window": "Time between an unhealthy report and a resumed report. Observation/publication delays make it neither an exact halt interval nor a rigorous bound.",
    "scheduled_maintenance_status_window": "Separate from unplanned outages; expected downtime is not actual measured downtime.",
    "revert": "An included execution failure may still consume gas; it is not by itself an outage, fork or consensus failure."
  },
  "comparability_limitations": [
    "Do not sum these heterogeneous durations or rank annual uptime from this selected list.",
    "No chain-wide annual availability, fork frequency, reorg-depth distribution or transaction finality p95 is established.",
    "Status-feed absence does not prove zero incidents; feeds may be incomplete and differ in definitions and retention.",
    "L2 sequencer acceptance, L1 data availability/finality and assertion settlement are different milestones.",
    "Contract-registry transaction failures in the fee census measure that workload only; they do not measure chain-wide availability."
  ],
  "events": [
    {
      "id": "polygon_heimdall",
      "chain": "Polygon",
      "date": "2025-07-30",
      "layer": "Heimdall consensus",
      "source_ids": [
        "polygon_heimdall"
      ],
      "source_url": "https://forum.polygon.technology/t/heimdall-v2-v0-2-16-mainnet/21178",
      "summary": "The emergency release identifies a Heimdall mainnet halt at height 25,723,062 around 09:21 UTC. It gives no recovery timestamp.",
      "windows": [
        {
          "start_utc": "2025-07-30T09:21:00Z",
          "end_utc": null,
          "kind": "provider_reported_heimdall_halt_start",
          "precision": "minute",
          "approximate": true,
          "elapsed_seconds": null
        }
      ],
      "block_production_assessment": "Heimdall halt established; this source alone does not establish the Bor execution-halt interval.",
      "actual_production_halt_seconds": null,
      "finality_disruption_seconds": null,
      "caveat": "The 11:42 forum publication is a patch announcement, not a demonstrated recovery time. Do not derive 2h21m downtime from it.",
      "within_census_period": true
    },
    {
      "id": "polygon_milestone",
      "chain": "Polygon",
      "date": "2025-09-10",
      "layer": "Milestone / node recovery",
      "source_ids": [
        "polygon_milestone"
      ],
      "source_url": "https://forum.polygon.technology/t/bor-v2-2-11-beta2-and-heimdall-v0-3-1-hot-fix-release-for-polygon-mainnet/21284",
      "summary": "Official recovery steps purge local checkpoint/milestone whitelist entries and rewind Bor to block 76,273,069, immediately before an incorrect milestone. A milestone-deletion Heimdall hard fork was scheduled around 15:00 UTC.",
      "windows": [],
      "block_production_assessment": "A corrective recovery is documented, but no precise network-wide production interruption is established.",
      "actual_production_halt_seconds": null,
      "finality_disruption_seconds": null,
      "caveat": "Scheduled hard-fork activation is not incident recovery. The rewind instruction is not a measurement of universal rollback depth, affected transactions, or annual fork rate.",
      "within_census_period": true
    },
    {
      "id": "polygon_rpc",
      "chain": "Polygon",
      "date": "2025-12-17/18",
      "layer": "RPC availability / node lag / finality lag",
      "source_ids": [
        "polygon_rpc"
      ],
      "source_url": "https://forum.polygon.technology/t/polygon-pos-rpc-incident-post-incident-summary/21487",
      "summary": "The provider reports stalled Bor nodes, impaired RPC availability and delayed finality, while block production continued throughout. Some RPC providers stayed operational.",
      "windows": [],
      "block_production_assessment": "Provider explicitly reports uninterrupted block production.",
      "actual_production_halt_seconds": 0,
      "finality_disruption_seconds": null,
      "caveat": "Zero production halt here is the provider claim for this incident; it does not mean zero failed client requests or zero finality delay. No precise finality recovery interval is given; the summary was published December 18.",
      "within_census_period": true
    },
    {
      "id": "polygon_producer",
      "chain": "Polygon",
      "date": "2026-09-19",
      "layer": "Block-producer degradation",
      "source_ids": [
        "polygon_producer"
      ],
      "source_url": "https://status.polygon.technology/incidents/xjb7py3e",
      "summary": "Status narrative reports degraded block production and delayed confirmations from approximately 19:15 UTC, with healthy service confirmed after producer rotation and a fix at 19:35.",
      "windows": [
        {
          "start_utc": "2026-09-19T19:15:00Z",
          "end_utc": "2026-09-19T19:35:00Z",
          "kind": "provider_narrative_degradation_window",
          "precision": "minute",
          "approximate": true,
          "elapsed_seconds": 1200.0
        },
        {
          "start_utc": "2026-09-19T20:05:54.371Z",
          "end_utc": "2026-09-19T20:06:29.411Z",
          "kind": "conflicting_component_status_metadata",
          "precision": "millisecond",
          "elapsed_seconds": 35.04
        }
      ],
      "block_production_assessment": "Degradation, not a demonstrated continuous block-production halt.",
      "actual_production_halt_seconds": null,
      "finality_disruption_seconds": null,
      "caveat": "The 20-minute narrative conflicts with later component-impact metadata lasting 35.040 seconds. Use the narrative with an explicit qualifier; neither is an independent uptime measurement.",
      "within_census_period": true
    },
    {
      "id": "arbitrum_batch",
      "chain": "Arbitrum One",
      "date": "2026-01-07",
      "layer": "L1 batch posting",
      "source_ids": [
        "arbitrum_batch"
      ],
      "source_url": "https://status.arbitrum.io/cmk3hc4qf03be1et0bxvpym69",
      "summary": "An infrastructure issue prevented posting batches to Ethereum. Sequencer and batch-poster components are labeled degraded. The report does not establish a complete L2 execution halt.",
      "windows": [
        {
          "start_utc": "2026-01-07T02:30:36.263Z",
          "end_utc": "2026-01-07T06:32:17.170Z",
          "kind": "incident_management_window",
          "precision": "millisecond",
          "elapsed_seconds": 14500.907
        }
      ],
      "block_production_assessment": "No full sequencer-production halt established by the cited incident.",
      "actual_production_halt_seconds": null,
      "finality_disruption_seconds": null,
      "caveat": "Embedded timestamps span 4h01m40.907s, approximately 4h02m. The page displays 4h01m. This is the report window, not measured duration of each transaction finality delay.",
      "within_census_period": true
    },
    {
      "id": "arbitrum_assertion",
      "chain": "Arbitrum One",
      "date": "2026-02-05/06",
      "layer": "L1 assertion posting",
      "source_ids": [
        "arbitrum_assertion"
      ],
      "source_url": "https://status.arbitrum.io/cml9znj2r00cjuy23b9699i0v",
      "summary": "The validator incident concerns delayed assertions; resolution says an assertion was posted. This affects assertion settlement rather than establishing a block-production outage.",
      "windows": [
        {
          "start_utc": "2026-02-05T17:00:00Z",
          "end_utc": "2026-02-06T04:37:00Z",
          "kind": "incident_management_window",
          "precision": "minute",
          "elapsed_seconds": 41820.0
        }
      ],
      "block_production_assessment": "No sequencer-production halt established.",
      "actual_production_halt_seconds": null,
      "finality_disruption_seconds": null,
      "caveat": "11h37m is the displayed incident window; it is neither a per-transaction finality measure nor an execution-halt duration.",
      "within_census_period": true
    },
    {
      "id": "arbitrum_feed",
      "chain": "Arbitrum One / Nova",
      "date": "2026-05-20",
      "layer": "Sequencer feed connectivity",
      "source_ids": [
        "arbitrum_feed"
      ],
      "source_url": "https://status.arbitrum.io/cmpfn10dh00o0peksqhe3iqz7",
      "summary": "Intermittent feed connections were degraded; the incident report lists the feed components on both networks.",
      "windows": [
        {
          "start_utc": "2026-05-20T19:55:00Z",
          "end_utc": "2026-05-20T20:11:00Z",
          "kind": "incident_management_window",
          "precision": "minute",
          "elapsed_seconds": 960.0
        }
      ],
      "block_production_assessment": "Feed disruption does not establish chain halt.",
      "actual_production_halt_seconds": null,
      "finality_disruption_seconds": null,
      "caveat": "16-minute displayed report window; no annual availability denominator.",
      "within_census_period": true
    },
    {
      "id": "base_halt",
      "chain": "Base",
      "date": "2025-08-05",
      "layer": "Mainnet block production",
      "source_ids": [
        "base_halt"
      ],
      "source_url": "https://status.base.org/incidents/kdq3t8s13gfs",
      "summary": "The postmortem attributes a 33-minute production halt to sequencer failover selecting an instance not ready to produce blocks. Manual transfer to a healthy instance restored production.",
      "windows": [
        {
          "start_utc": "2025-08-05T06:07:00Z",
          "end_utc": "2025-08-05T06:40:00Z",
          "kind": "provider_postmortem_production_halt",
          "precision": "minute",
          "elapsed_seconds": 1980.0
        },
        {
          "start_utc": "2025-08-05T06:07:47.000Z",
          "end_utc": "2025-08-05T06:41:00.000Z",
          "kind": "incident_management_window",
          "precision": "millisecond",
          "elapsed_seconds": 1993.0
        }
      ],
      "block_production_assessment": "Provider-confirmed mainnet block-production halt.",
      "actual_production_halt_seconds": 1980,
      "finality_disruption_seconds": null,
      "caveat": "33 minutes is explicitly reported in the postmortem, not independently reconstructed from all block headers. Status resolution at 06:41 was later than production recovery.",
      "within_census_period": true
    },
    {
      "id": "base_june",
      "chain": "Base",
      "date": "2026-06-25/26",
      "layer": "Mainnet block production",
      "source_ids": [
        "base_june"
      ],
      "source_url": "https://status.base.org/incidents/5c4gm1wzbjs4",
      "summary": "Status updates describe two stalls, with a problematic block preventing subsequent production and node restarts needed for recovery. Production resumed between the episodes.",
      "windows": [
        {
          "start_utc": "2026-06-25T16:03:00Z",
          "end_utc": "2026-06-25T17:51:00Z",
          "kind": "first_unhealthy_to_resumed_reporting_window",
          "precision": "minute",
          "elapsed_seconds": 6480.0
        },
        {
          "start_utc": "2026-06-26T15:33:00Z",
          "end_utc": "2026-06-26T15:47:00Z",
          "kind": "second_unhealthy_to_resumed_reporting_window",
          "precision": "minute",
          "elapsed_seconds": 840.0
        },
        {
          "start_utc": "2026-06-25T16:03:16.015Z",
          "end_utc": "2026-06-26T20:03:41.036Z",
          "kind": "incident_management_window",
          "precision": "millisecond",
          "elapsed_seconds": 100825.021
        }
      ],
      "block_production_assessment": "Two block-production stalls established; exact starts and restoration instants not independently measured.",
      "actual_production_halt_seconds": null,
      "finality_disruption_seconds": null,
      "caveat": "108- and 14-minute update intervals are reporting windows, not rigorous downtime bounds. The approximately 28-hour open incident must not be treated as continuous halt.",
      "within_census_period": true
    },
    {
      "id": "base_safe_head",
      "chain": "Base",
      "date": "2026-07-28",
      "layer": "Data batching / safe head",
      "source_ids": [
        "base_safe_head"
      ],
      "source_url": "https://status.base.org/incidents/j6y12tshwkcg",
      "summary": "The report explicitly says new block production continued normally; Ethereum batch submission and safe-head progression were delayed.",
      "windows": [
        {
          "start_utc": "2026-07-28T13:10:59.378Z",
          "end_utc": "2026-07-28T15:13:23.957Z",
          "kind": "incident_management_window",
          "precision": "millisecond",
          "elapsed_seconds": 7344.579
        }
      ],
      "block_production_assessment": "Provider explicitly reports normal new-block production.",
      "actual_production_halt_seconds": 0,
      "finality_disruption_seconds": null,
      "caveat": "Approximately 2h02m25s management window, not measured downtime. Safe-head delay is distinct from finalized-L1 inclusion and assertion settlement.",
      "within_census_period": true
    },
    {
      "id": "hyper_maintenance",
      "chain": "Hyperliquid L1",
      "date": "2026-10-03",
      "layer": "Scheduled network upgrade",
      "source_ids": [
        "hyper_maintenance"
      ],
      "source_url": "https://hyperliquid.statuspage.io/incidents/pfwvxl29cjpl",
      "summary": "The announcement expected about ten minutes of downtime. Maintenance was marked in progress at 09:00 and completed at 09:20 UTC.",
      "windows": [
        {
          "start_utc": "2026-10-03T09:00:00Z",
          "end_utc": "2026-10-03T09:20:00Z",
          "kind": "scheduled_maintenance_status_window",
          "precision": "minute",
          "elapsed_seconds": 1200.0
        }
      ],
      "block_production_assessment": "Expected interruption disclosed; actual chain halt length not established.",
      "actual_production_halt_seconds": null,
      "finality_disruption_seconds": null,
      "announced_expected_downtime_seconds": 600,
      "caveat": "The 20-minute maintenance window is not a measured 20-minute outage. This event is current context outside the October 2024\u2013September 2026 census.",
      "within_census_period": false
    },
    {
      "id": "hyper_api",
      "chain": "Hyperliquid",
      "date": "2025-07-29",
      "layer": "Order API congestion",
      "source_ids": [
        "hyper_api"
      ],
      "source_url": "https://t.me/s/hyperliquid_announcements/404",
      "summary": "Official announcement gives approximately 14:10\u201314:47 UTC order delays and says blockchain consensus and HyperEVM were unaffected, with normal-rate block production.",
      "windows": [
        {
          "start_utc": "2025-07-29T14:10:00Z",
          "end_utc": "2025-07-29T14:47:00Z",
          "kind": "provider_reported_order_api_delay",
          "precision": "minute",
          "approximate": true,
          "elapsed_seconds": 2220.0
        }
      ],
      "block_production_assessment": "Provider explicitly reports unaffected blockchain and HyperEVM.",
      "actual_production_halt_seconds": 0,
      "finality_disruption_seconds": null,
      "caveat": "37-minute API disruption can matter to traders without being a HyperEVM outage. Do not infer chain downtime from API errors.",
      "within_census_period": true
    },
    {
      "id": "solana_postmortem",
      "chain": "Solana",
      "date": "2024-02-06",
      "layer": "Consensus / block finalization",
      "source_ids": [
        "solana_postmortem"
      ],
      "source_url": "https://solana.com/news/02-06-24-solana-mainnet-beta-outage-report",
      "summary": "The postmortem reports finalization halted at 09:53 UTC and consensus progress resumed at 14:55. The status-feed narrative separately reports production resumed at 14:57.",
      "windows": [
        {
          "start_utc": "2024-02-06T09:53:00Z",
          "end_utc": "2024-02-06T14:55:00Z",
          "kind": "provider_postmortem_consensus_interruption",
          "precision": "minute",
          "elapsed_seconds": 18120.0
        },
        {
          "start_utc": "2024-02-06T09:53:00Z",
          "end_utc": "2024-02-06T14:57:00Z",
          "kind": "provider_status_production_interruption",
          "precision": "minute",
          "elapsed_seconds": 18240.0
        }
      ],
      "block_production_assessment": "Provider-confirmed roughly five-hour interruption, outside the study period.",
      "actual_production_halt_seconds": 18240,
      "finality_disruption_seconds": 18120,
      "caveat": "302 minutes is the postmortem consensus interval; 304 minutes is the status narrative production interval. These differ by endpoint/definition. Do not count this February event in October 2024\u2013September 2026.",
      "secondary_source_ids": [
        "solana_feed"
      ],
      "within_census_period": false
    }
  ],
  "solana_feed_assessment": {
    "source_id": "solana_feed",
    "observation": "The fetched feed lists February 6, 2024 as its newest incident; no newer incident appears in that response.",
    "implication": "No in-period halt duration can be derived from this feed alone. Do not convert missing entries into 100% uptime.",
    "in_period_halt_duration_seconds": null
  },
  "recommended_compact_copy": [
    {
      "chain": "Polygon",
      "text": "July 2025: Heimdall halted around 09:21 UTC; recovery duration unverified. September 2026: about 20 minutes of reported producer degradation, with conflicting component timestamps. The September 2025 milestone fix documents recovery, not a measured annual fork rate."
    },
    {
      "chain": "Arbitrum One",
      "text": "January 2026: batch-posting degradation reported for approximately 4h02m. This is the incident window; a complete execution halt is not established. Assertion settlement, Ethereum data finality and sequencer speed are separate."
    },
    {
      "chain": "Base",
      "text": "August 2025: provider-confirmed 33-minute block-production halt, 06:07\u201306:40 UTC. June 2026: two further documented stalls; update intervals are not precise downtime measurements."
    },
    {
      "chain": "Hyperliquid",
      "text": "October 3, 2026: scheduled 09:00\u201309:20 UTC maintenance, with about ten minutes downtime expected rather than measured. July 2025: roughly 37 minutes of API delays; the provider says HyperEVM and block production were unaffected."
    },
    {
      "chain": "Solana",
      "text": "No newer incident than February 2024 appears in the retrieved feed. That roughly five-hour interruption lies outside this two-year census. Feed absence does not establish audited uptime."
    }
  ],
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