Base Outage History

Started Oct 10, 2025, 09:40 PM UTC· resolved Oct 11, 2025, 12:35 AM UTC

1. identified Oct 10, 2025, 09:40 PM UTC

   Heavy transaction volume on Base L2 is causing delays in batching data to Ethereum. Node operators may experience node client syncing delays and applications on Base may notice a lagging safe head. Block building (unsafe head) continues to function normally.

2. identified Oct 10, 2025, 10:54 PM UTC

   The safe head is still lagging behind, and the Base sequencing is currently limiting the amount of calldata it can include in L2 blocks. This is to ensure the safe head can progress on L1. Users may experience delays in transaction inclusion, and potentially a high rate of transaction drops.

3. resolved Oct 11, 2025, 12:35 AM UTC

   This incident has been resolved. Base chain is functioning properly.

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Started Sep 22, 2025, 12:02 AM UTC· resolved Sep 22, 2025, 12:37 AM UTC

1. monitoring Sep 22, 2025, 12:02 AM UTC

   Flashblocks were unavailable for ~10 minutes. We've identified the root cause and implemented a fix. We're currently monitoring the situation.

2. resolved Sep 22, 2025, 12:37 AM UTC

   This incident has been resolved.

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Started Sep 11, 2025, 05:18 PM UTC· resolved Sep 11, 2025, 06:03 PM UTC

1. identified Sep 11, 2025, 05:18 PM UTC

   Base Sepolia Preconf Flashblocks RPC started experiencing downtime at 12:45pm ET. The issue has been identified and we are working to restore service.

2. monitoring Sep 11, 2025, 05:32 PM UTC

   A fix has been implemented and we are monitoring the results.

3. resolved Sep 11, 2025, 06:03 PM UTC

   The incident has been resolved.

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Started Aug 15, 2025, 07:56 PM UTC· resolved Aug 15, 2025, 08:22 PM UTC

1. identified Aug 15, 2025, 07:56 PM UTC

   Base engineering team is aware of an issue causing a halt on the Sepolia testnet. We're working to get block production healthy as soon as possible.

2. monitoring Aug 15, 2025, 08:17 PM UTC

   Block building failures have been mitigated. We will continue to monitor the block production health.

3. resolved Aug 15, 2025, 08:22 PM UTC

   This incident has been resolved.

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Started Aug 05, 2025, 06:07 AM UTC· resolved Aug 05, 2025, 06:41 AM UTC

1. investigating Aug 05, 2025, 06:15 AM UTC

   Base mainnet chain is currently stalled

2. investigating Aug 05, 2025, 06:43 AM UTC

   We are continuing to investigate this issue.

3. monitoring Aug 05, 2025, 06:44 AM UTC

   Issue's been identified and fixed, we're now monitoring to ensure nothing else comes up

4. resolved Aug 05, 2025, 09:17 AM UTC

   The incident has been resolved

5. postmortem Aug 05, 2025, 05:02 PM UTC

   On August 5th 2025, we experienced a 33 minute network disruption that halted block production on Base Chain Mainnet. We want to share what happened, how we addressed the issue, and the steps we are taking to prevent similar incidents in the future. ### **What Happened** To ensure high chain uptime and minimize single points of failure, we operate several [sequencer instances](https://docs.optimism.io/connect/resources/glossary#sequencer-mode) in a highly available \(HA\) cluster. The cluster is managed by [Conductor](https://github.com/ethereum-optimism/optimism/tree/develop/op-conductor), an OP Stack component responsible for the reliability and availability of the system. At 6:07am UTC, the active sequencer began to fall behind due to onchain activity. Conductor detected this and performed an automated handoff to a new sequencer, a standard procedure designed to maintain chain uptime. However, the new sequencer was in the process of being provisioned and was unable to produce blocks. Typically if an unhealthy sequencer is elected, it does another handoff. Since Conductor was not yet fully enabled on this sequencer, it was unable to initiate another handoff. At 6:09am UTC, our monitoring systems detected this issue, and our team was paged to investigate. By 6:12am, an incident was formally declared, and our team began taking steps to resume block building. ### **How We Mitigated the Issue** Our team took the following steps to resume block building: 1. **Paused Conductor**: We manually paused our HA software to prevent further automated leadership transfers. 2. **Started a healthy sequencer**: We manually transferred leadership from the unhealthy sequencer to a healthy sequencer. Planning the transfer took several minutes to ensure we did not re-org the chain. By 6:40am UTC, the network was fully recovered, resulting in a total downtime of 33 minutes. ### **What We’re Doing to Prevent This in the Future** **System Improvements:** We will be updating our infrastructure to ensure that when a sequencer is added to the Conductor cluster, it is always able to transfer leadership if elected. **Enhanced Testing:** We will test and deploy these fixes as soon as possible to ensure the robustness of our automated systems.

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Started May 28, 2025, 02:40 PM UTC· resolved May 28, 2025, 06:09 PM UTC

1. investigating May 28, 2025, 02:40 PM UTC

   Safe head is currently trailing the unsafe head on Base Mainnet. We're working to optimize batching performance to restore normal progression. For time-sensitive operations, we recommend: * Use higher fees for time-sensitive transactions * Ensure retry logic is in place We’ll continue to post updates as we progress toward a resolution.

2. identified May 28, 2025, 03:01 PM UTC

   We've identified the cause of the safe head latency as an issue with batching performance. Batches are now posting, and we're working to close the gap between the safe and unsafe heads.

3. monitoring May 28, 2025, 04:32 PM UTC

   Batching performance has recovered and safe head is advancing normally. We’re continuing to monitor to ensure the delta stays within expected bounds.

4. resolved May 28, 2025, 06:09 PM UTC

   This incident has been resolved.

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Started May 21, 2025, 03:30 PM UTC· resolved May 21, 2025, 07:00 PM UTC

1. identified May 21, 2025, 03:30 PM UTC

   Base Mainnet safe head is lagging behind unsafe head. We're actively working to ensure performance of the batching system in order for safe head to progress quickly.

2. identified May 21, 2025, 07:27 PM UTC

   We are continuing to work on a fix for this issue.

3. resolved May 21, 2025, 07:28 PM UTC

   This incident has been resolved.

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Started May 16, 2025, 10:16 PM UTC· resolved May 17, 2025, 12:23 AM UTC

1. investigating May 16, 2025, 10:16 PM UTC

   Confirmed reports that wss://sepolia.flashblocks.base.org/ws is returning 429 (Too many requests) or 404 (Not Found), we're aware and investigating the issue.

2. investigating May 16, 2025, 10:17 PM UTC

   We are continuing to investigate this issue.

3. resolved May 17, 2025, 12:23 AM UTC

   This incident has been resolved.

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Started May 13, 2025, 03:23 PM UTC· resolved May 17, 2025, 07:45 PM UTC

1. monitoring May 13, 2025, 03:23 PM UTC

   We're currently observing some localized delays in transaction confirmation due to increased activity and dynamic fee conditions. The network is processing transactions normally, but some may take longer than expected to be included. We're closely monitoring the situation to ensure smooth performance across the board. If you're seeing delays, please make sure you're using competitive fees and have retry logic in place for time-sensitive operations.

2. monitoring May 14, 2025, 05:00 PM UTC

   Follow-up for Node Operators If your node has fallen behind, please review our performance tuning recommendations: https://docs.base.org/chain/node-performance Still seeing issues after applying those changes? Reach out in the #node-operators channel of the Base Discord (https://base.org/discord)—we’re happy to help.

3. monitoring May 17, 2025, 03:39 PM UTC

   The network has been functioning well over the past few days, we've implemented fixes and improvements to transaction processing pipelines, and we're closely monitoring the situation to ensure smooth performance going forward

4. resolved May 17, 2025, 07:45 PM UTC

   This incident has been resolved.

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Started May 01, 2025, 06:09 PM UTC· resolved May 01, 2025, 09:08 PM UTC

1. identified May 01, 2025, 06:09 PM UTC

   We've identified an issue causing some external Base Sepolia (Testnet) nodes to periodically fall out of sync with the tip of the chain. This issue is isolated to our test network — Base mainnet is unaffected, and all funds remain safe. We're actively investigating the root cause and will provide updates as we learn more. If you're operating a Sepolia testnet node, no action is needed at this time. We'll keep you informed as we make progress toward a resolution.

2. resolved May 01, 2025, 09:08 PM UTC

   This incident has been resolved.

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Started Apr 30, 2025, 09:36 PM UTC· resolved Apr 30, 2025, 10:37 PM UTC

1. identified Apr 30, 2025, 09:36 PM UTC

   Requests sent to mainnet.base.org will periodically hang

2. monitoring Apr 30, 2025, 09:50 PM UTC

   A fix has been implemented and we are monitoring the results.

3. resolved Apr 30, 2025, 10:37 PM UTC

   This incident has been resolved.

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Started Apr 30, 2025, 07:22 PM UTC· resolved Apr 30, 2025, 08:02 PM UTC

1. identified Apr 30, 2025, 07:22 PM UTC

   external base sepolia nodes might be stalled

2. resolved Apr 30, 2025, 08:02 PM UTC

   This incident has been resolved.

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Started Apr 29, 2025, 09:14 PM UTC· resolved May 01, 2025, 06:43 PM UTC

1. identified Apr 29, 2025, 09:14 PM UTC

   The issue has been identified and a fix is being implemented.

2. resolved May 01, 2025, 06:43 PM UTC

   flashblocks are re-enabled

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Started Apr 23, 2025, 03:46 PM UTC· resolved Apr 23, 2025, 06:31 PM UTC

1. monitoring Apr 23, 2025, 03:46 PM UTC

   Blockscout and Basescan are currently experiencing intermittent issues alongside elevated network throughput. Their teams are aware and actively working on a fix. The Base network itself remains fully operational and unaffected. If you need an explorer in the meantime, here are a couple of alternative options: • https://base.thesuperscan.io/ • https://base.dex.guru/ We’ll send updates as we receive confirmation that the issues have been resolved.

2. resolved Apr 23, 2025, 06:31 PM UTC

   This incident has been resolved.

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Started Apr 15, 2025, 10:26 PM UTC· resolved Apr 16, 2025, 05:05 AM UTC

1. investigating Apr 15, 2025, 10:26 PM UTC

   We are currently investigating this issue.

2. monitoring Apr 15, 2025, 10:36 PM UTC

   The block production has resumed and we're monitoring

3. monitoring Apr 15, 2025, 10:54 PM UTC

   We are continuing to monitor for any further issues.

4. monitoring Apr 15, 2025, 10:54 PM UTC

   We are continuing to monitor for any further issues.

5. resolved Apr 16, 2025, 05:05 AM UTC

   Sepolia testnet is now operating normally

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Started Apr 09, 2025, 03:21 AM UTC· resolved Apr 09, 2025, 07:36 PM UTC

1. investigating Apr 09, 2025, 03:21 AM UTC

   We are currently investigating this issue.

2. investigating Apr 09, 2025, 03:23 AM UTC

   We are continuing to investigate this issue.

3. monitoring Apr 09, 2025, 04:39 AM UTC

   A fix has been implemented and we are monitoring the results.

4. resolved Apr 09, 2025, 07:36 PM UTC

   This incident has been resolved.

5. postmortem Apr 09, 2025, 07:37 PM UTC

   # Incident summary On April 9th at approximately 01:15 UTC, Base’s batcher experienced an increase in data that was pending submission to L1. This was due to a sudden spike in transaction volume on Base. To help stabilize the network, the Base sequencer reduced block sizes to allow the batcher to catch up \(posting all remaining & new data to L1 blobs\). This lasted for 3 hours which during that time, our block sizes were roughly 33% \(20 Mgas\) of the 60 Mgas target. While block sizes were reduced, some users experienced delayed or failed transactions, as transactions sat in the mempool longer than expected and some were eventually dropped. Once the backlog cleared and normal batcher operations resumed, block sizes increased to process the pending activity. This spike in block size caused some node operators to fall behind, leading to syncing issues with their nodes. This issue has been fully resolved. At no point were user funds at risk — all assets remained safe throughout the incident. # Impact * **User transactions:** Some transactions were delayed or dropped from the mempool for a brief period of time, leading to some users experiencing failures and having to resubmit. * **Node operators:** Larger blocks put extra strain on node resources, resulting in slower synchronization and, in some cases, stalled node performance. # Resolution * The batcher has fully recovered, and blocks are now being processed as expected. * We have published fresh snapshot links \(see below\) to help node operators rapidly restore any behind nodes. # Recommendations for node operators * **Restore from snapshot if behind:** If your node falls significantly behind the chain head, [restoring from a snapshot](https://docs.base.org/chain/run-a-base-node#snapshots) is the fastest way to resync. * **Ensure your setup is optimized:** Monitor your node logs for signs of high resource usage or network latency, and ensure your setup has sufficient CPU, RAM, and disk I/O capacity to handle larger blocks. We recommend using a locally attached NVMe SSD for optimal disk performance. * **Consider redundancy & load-balancing:** Running a secondary node or using a load balancer can help maintain uptime and stability if you process a significant transaction volume. # Next steps * **Refine batcher logic:** We are iterating on our batching mechanism to prevent large backlog scenarios due to L1 congestion and ensure smoother block size transitions. * **Improve mempool management:** We plan to scale transaction pool systems to reduce dropped transactions. * **Expand operator guidance:** Additional tools and documentation will be released for troubleshooting and faster sync recovery. # User guidance * **Resubmit dropped transactions:** If your transaction was dropped as a result of the aforementioned issues, simply resubmit it with an appropriate gas fee. * **Utilize stable RPC providers:** If your self-hosted node remains out of sync, consider routing through a [third-party RPC provider](https://docs.base.org/chain/node-providers) while you recover or resync. ‌ For support or questions, please don’t hesitate to contact us in the [Base Discord](https://base.org/discord), we're happy to help you there.

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Started Apr 02, 2025, 09:19 PM UTC· resolved Apr 02, 2025, 09:27 PM UTC

1. identified Apr 02, 2025, 09:19 PM UTC

   Unsafe blocks are not being created on the Sepolia testnet. The team is working to mitigate the incident.

2. monitoring Apr 02, 2025, 09:23 PM UTC

   The incident is resolved and unsafe blocks are now progressing. We'll continue to monitor the situation.

3. resolved Apr 02, 2025, 09:27 PM UTC

   Unsafe blocks and Batching are now caught up and operating normally.

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Started Mar 20, 2025, 03:01 PM UTC· resolved Mar 21, 2025, 06:07 PM UTC

1. investigating Mar 20, 2025, 03:01 PM UTC

   We're investigating an issue where eth_sendRawTransaction calls on Base Sepolia (Testnet) are resulting in errors for a subset of transactions. We're working to identify the root cause and will provide updates as we learn more. Base Mainnet is unaffected.

2. monitoring Mar 20, 2025, 03:32 PM UTC

   A fix has been implemented and we are monitoring the results.

3. resolved Mar 21, 2025, 06:07 PM UTC

   This incident has been resolved.

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Started Mar 05, 2025, 09:27 AM UTC· resolved Mar 05, 2025, 04:30 PM UTC

1. investigating Mar 05, 2025, 09:27 AM UTC

   The Sepolia batcher was not submitting batches since the L1 Pectra upgrade went live. This is due to an issue on L1, we're currently monitoring. Unsafe head is unaffected

2. monitoring Mar 05, 2025, 03:03 PM UTC

   A fix has been implemented and we're monitoring the result

3. resolved Mar 05, 2025, 04:30 PM UTC

   Safe head is current. This incident has been resolved

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Started Jan 31, 2025, 12:22 PM UTC· resolved Jan 31, 2025, 12:31 PM UTC

1. investigating Jan 31, 2025, 12:22 PM UTC

   We're investigating an issue where eth_sendRawTransaction calls on Base Sepolia (testnet) are resulting in errors for a subset of transactions. We're working to identify the root cause and will provide updates as we learn more. Base mainnet is unaffected.

2. resolved Jan 31, 2025, 12:31 PM UTC

   Unhealthy reth mempool nodes lead to an increased error rate. We have routed traffic away from these nodes and the issue is now resolved.

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Started Jan 29, 2025, 04:43 PM UTC· resolved Jan 31, 2025, 03:00 PM UTC

1. identified Jan 29, 2025, 04:43 PM UTC

   Some transactions on Base are taking slightly longer to confirm due to a full mempool. We are increasing the mempool size to alleviate this issue. The network remains fully operational, and transactions will continue to be processed as usual. If you notice delays, they should resolve as the mempool clears. We are monitoring the situation and will continue to provide updates.

2. monitoring Jan 29, 2025, 07:57 PM UTC

   We've identified that some transactions in the mempool are being evicted due to low fees. This is affecting transactions submitted with nonces far apart, where later transactions may be dropped if earlier ones remain underpriced. If your application is impacted, ensure it includes retry logic and adjusts fees when resubmitting to account for potential base fee increases.

3. resolved Feb 03, 2025, 10:31 PM UTC

   This incident has been resolved.

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Started Nov 27, 2024, 06:00 AM UTC· resolved Nov 27, 2024, 09:00 AM UTC

1. resolved Nov 27, 2024, 02:56 PM UTC

   The Sepolia batcher was not submitting valid batches for a period of 2 hours on 11/27 between 06:00 and 09:00 UTC. Safe head feel behind unsafe for the duration of the incident.

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Started Nov 23, 2024, 12:37 AM UTC· resolved Dec 03, 2024, 05:28 PM UTC

1. investigating Nov 23, 2024, 12:37 AM UTC

   We are currently investigating this issue.

2. resolved Dec 03, 2024, 05:28 PM UTC

   This incident has been resolved.

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