Incident History

This incident has been resolved. Thank you for your patience and understanding as we addressed this issue. A detailed root cause analysis will be shared as soon as it is available.

Please refer to the combined summary in this related incident: https://www.githubstatus.com/incidents/s65j9gslmfm8

On July 25, 2026, between 09:07 and 10:04 UTC, the GPT-5.2, GPT-5.3-Codex, GPT-5.4, GPT-5.4 Mini, GPT-5.6 Sol, GPT-5.6 Terra and GPT-5.6 Luna models experienced degraded availability in GitHub Copilot products and IDE surfaces. Requests to these models had an average failure rate of 5.6%. Other Copilot models remained available as alternatives.The degradation was caused by an issue with an upstream model provider. Success rates returned to normal after the upstream issue was mitigated, and we continued monitoring before resolving the incident. We are working on improving the automated failover for the affected models to prevent similar incidents in the future.

On July 25, 2026, GitHub Actions experienced two related periods of degradation that caused some workflow runs to be delayed by more than 5 minutes or end with infrastructure failures. First period (08:45 – 09:13 UTC): During planned maintenance on a critical-path Redis cluster for Actions, one participating region was left in a degraded state. Separately, an independent capacity operation temporarily removed another region from the cluster and redirected its traffic to the degraded region. This created cross-region inconsistencies in job-assignment state, causing workflow runs to be delayed, exhaust retries, or fail outright. At peak, about 7% of runs were delayed by more than 5 minutes, and 25% of runs failed with an infrastructure error during the course of the incident. We mitigated the incident at 09:13 UTC by returning traffic to its normal distribution. Second period (12:08 – 12:48 UTC): As part of mitigating the first incident, traffic was returned to the regional instance that was still undergoing its capacity increase. Multiple Redis nodes in the scaling region experienced failures, increasing traffic to healthy nodes and causing connection limits to be reached on many nodes. At peak, 30% of runs were delayed by more than 5 minutes, and 60% of runs failed with an infrastructure error during the course of the incident. We mitigated the incident at 12:48 UTC by redirecting workflow traffic away from the scaling region. We are adding stronger regional health and capacity checks before maintenance and requiring a stable observation period before restoring traffic. We are also improving automated connection resiliency, and partnering with our platform dependency to automatically detect and remediate unhealthy cluster members and shard imbalance. More generally, we already had work underway to improve the resiliency and scale of this piece of Actions infrastructure.

Between July 24, 19:17 UTC and July 24, 20:02 UTC, users were unable to create pull requests due to a database schema change. In total, 113,930 pull request creation attempts were impacted across 50,904 users, with an average error rate of 1.75% and a maximum error rate of 2.25% for all requests to Pull Requests service. Existing pull requests and other GitHub functionality were not affected. The issue was resolved by reverting the change to the affected database, upon which pull request creation immediately resumed.The root cause was related to a backfill workflow into the Vitess keyspace hosting Pull Request data. The backfill Vitess command encountered errors and increased VReplication lag, and the workflow was canceled at 19:17 UTC. The cancellation executed a misunderstood Vitess codepath that dropped the backing table to the target keyspace, leaving a non-existent reference that resulted in errors creating Pull Requests. The mitigation was executing a command to drop the vschema reference to the dropped table, allowing Pull Request creation to resume.We are adding stronger pre-flight validation to our tooling to prevent similar issues and expanding lower-environment support to provide better test coverage end-to-end before promoting them to production. We're also fixing our backfill migration tooling to protect from this specific codepath.

On July 24th at 16:04 UTC, a loss of connectivity occurred in network paths in one of our three physical data center availability zones (AZs). This resulted in packet loss due to the remaining active paths becoming saturated. Our data centers use a leaf-spine switch fabric in each compute cage, and an aggregation layer interconnecting the spines from each cage within each AZ. The loss of connectivity affected links between one cage’s spine switches and the aggregation layer within that specific AZ. Workloads depending on compute resources in this cage became degraded due to packet loss, and exhibited intermittent errors: - Actions saw 10% of jobs fail during the impact window, and 5% of jobs succeeded but with delayed starts. - 27% of GitHub issues interactions saw slow requests or timeouts. - 4% of GitHub Copilot requests experienced errors, though most automatically retry. - 4% of git push operations saw impacts during the affected window. - Authentication requests saw increased latency during the affected window, but error rates, while elevated, were < 1% in all cases. We were able to mitigate the outage by re-routing affected connections to available fiber paths that were allocated for future capacity upgrades. Sufficient network capacity to eliminate packet loss was restored at 17:07, with most services showing full recovery by 17:16. All paths were restored and services healthy at 17:36. This incident affected 25% of available network interconnect capacity. Older cages utilize a 100Gbps network interface standard. To remove risk of reoccurrence, a planned upgrade to 400Gbps interfaces is being accelerated as much as possible, ensuring increased bandwidth available at all layers of the switch fabric for resiliency to path or device loss.

Between July 23, 2026 at 18:45 UTC and July 24, 2026 at 11:19 UTC, an abuse mitigation update caused some legitimate customers whose traffic was routed through our Central Europe and South America edge locations to be incorrectly blocked from GitHub.com. We estimate that approximately 0.25% of GitHub.com requests were affected during this period.

This was caused by an abuse mitigation configuration that incorrectly classified legitimate traffic. We mitigated the incident by reverting the update. We are adding validation and safeguards to prevent similar incorrect blocking in the future.

On July 23, 2026, between 07:08 and 09:39 UTC, several services experienced delays: 8% of actions workflow runs experienced an average run start delay of 10 minutes, 5% of webhook deliveries exceeded SLO, and code scanning, repos, notifications, issues and pull requests experienced increased latency over the life of the incident. The root cause of the incident was a node of our background job processing system which did not recover after entering scheduled host maintenance. The incident was mitigated by identifying the problematic shard and restoring its correct state, after which queue backlogs drained and services recovered. To speed mitigation, we have added monitors for nodes in this unhealthy state after maintenance operations. To prevent future recurrence, we are adapting our lifecycle automation to verify host rejoin after a scheduled reboot.

On July 22, 2026, between 19:36 UTC and 22:04 UTC, GitHub Actions experienced delayed and failed job starts on GitHub-hosted runners. The incident was caused by an unhealthy state in a backend data service responsible for provisioning hosted runners, preventing runner acquisition for a subset of workloads. During most of the incident, approximately 15% of workflow runs on hosted runners were delayed by more than 5 minutes, while roughly 1% failed to start.At 21:49 UTC, we restored the health of the backend data replication system, allowing provisioning to recover and the accumulated workflow backlog to drain. Service performance then returned to expected levels. We are improving provisioning-service resiliency, workload distribution, and capacity balancing to reduce the likelihood and impact of similar incidents.

On July 21, 2026, between 07:41 UTC and 11:57 UTC, the SSH Authentication service was degraded and some SSH connections failed to authenticate. On average, 12.2% of SSH authentication requests failed, peaking at 15.7%. Both user RSA keys and deploy keys were impacted. This was due to a change in how our SSH service handled one public-key authentication method that caused the affected authentication attempts to be rejected as invalid. We mitigated the incident by reverting the change, after which SSH authentication returned to normal. We are working to expand our automated test coverage for our SSH public-key authentication flows to catch more edge cases and to improve observability and alerting on SSH authentication failures, to reduce our time to detection and mitigation of issues like this one in the future.