On May 12, 2026, between 13:41 and 17:43 UTC, some services experienced delays in processing. For the Code Scanning service, 53% of check runs took over 15 minutes to complete. Additionally, notifications took an average of 22 minutes to be delivered and Slack integration webhooks took an average of 20 minutes to be delivered. The delays were caused by replication lag due to an internal database migration, resulting in insufficient worker capacity for our high rate of job enqueues. We mitigated the impact by scaling our processing workers to handle the increased load. All services returned to normal processing times after the mitigation was applied. We are working to create dedicated worker pools for some of our high usage shared queues to help prevent this in the future.
On May 11th, 2026, between 14:00 UTC and 14:33 UTC, HTTP-based Git read operations were degraded. On average, the error rate was 2.8% and peaked at 7.5% of requests to the service. This was due to resource exhaustion in a networking gateway between GitHub.com’s frontend service for Git operations and a dependency service that performs authentication and authorization. Following the initial spike, the frontend service became stuck in a degraded state in one of our data centers, increasing time to mitigation. We mitigated the incident by scaling the networking gateway and re-deploying the frontend service. To reduce our time to detection and mitigation in the future, we are adding auto-scaling to the networking gateway, and resolving a bug which caused the frontend service to remain degraded.
On May 7, 2026, between 04:12 UTC and 06:13 UTC, Copilot Cloud Agent and Copilot Code Review Agent sessions for pull requests were delayed or failed to start.The issue was caused by follow-up recovery work from a separate Pull Requests incident (https://www.githubstatus.com/incidents/f5pb5d5mr9yh). As part of that recovery, we ran a large database migration, which caused replication delays on several replica hosts.Although those replicas were not serving user traffic, our safeguards correctly treated the elevated replication lag as a signal to slow down writes to the affected database cluster. As a result, some pull request background processing was temporarily delayed. That processing is responsible for sending the internal events that Copilot agents use to begin work, so affected agents did not start until the database replicas caught up.The system recovered once replication lag returned to normal and pull request processing resumed. We are reviewing how this safeguard interacts with recovery migrations so we can reduce the chance of similar secondary impact during future incident recovery work.
On May 6, 2026 between 15:12 and 19:02 UTC creation of new pull request review threads on GitHub.com failed. This included new line comments and file comments on pull requests. Existing PRs and previously created comments were unaffected. This incident was caused by a 32-bit integer key reaching its maximum value in a Vitess lookup table used during PR thread creation. The primary table had been migrated to a 64-bit integer key but the Vitesse lookup table remained 32-bit. Once the values in the primary table passed the available 32-bit ID space in the lookup table, attempts to create new review threads began failing, resulting in near 100% failure rate for new thread creation requests. We mitigated the issue by updating the impacted lookup table definitions across all shards to use 64-bit integer column types, increasing the available ID range and restoring normal operation. Service was fully restored once the schema changes competed globally. To help prevent similar incidents, we are expanding existing monitoring of database columns to include Vitess lookup tables to notify in advance of any tables that is approaching a column size limit. This work is intended to provide earlier detection of columns approaching size limits before customer impact occurs.
On May 6, 2026 between 11:02 UTC and 11:13 UTC, users were unable to start or view Copilot Cloud Agent or remote sessions. During this time, requests to the session API returned errors, preventing users from creating new sessions or viewing existing ones. The issue was caused by a configuration change to the service's network routing that inadvertently removed the ingress path for the service. The team reverted the change at 11:13 UTC which restored service. The incident remained open until 11:59 UTC while the team verified full recovery. We are taking steps to improve our deployment validation process to prevent similar configuration changes from impacting production traffic in the future.
On May 6, 2026, from approximately 06:45 UTC to 09:15 UTC, GitHub Actions Standard Ubuntu hosted runners were degraded. 17.1% of jobs requesting a standard runner failed.This was caused by an unexpected data shape in the allocation configuration data for standard runners. That data was introduced as part of post-incident remediation work for an incident the previous day and caused new allocations to be blocked as load ramped up for the day. Removing that data at 08:51 allowed allocations to proceed and hosted runner pools to scale up and recover.We are updating the filter logic for this allocation data to be resilient to abnormal data shapes and improving monitoring to alert when allocations are blocked, allowing the team to respond before customer impact starts.
Between approximately 14:00 and 16:10 UTC on May 5, 2026, SSH-based Git operations experienced elevated latency and intermittent failures. On average, the error rate was 0.46% and peaked at 0.6% of SSH write requests. HTTP-based Git operations, including web UI and HTTPS clones, were not affected. The impact was caused by reduced SSH capacity at one of our data center sites. During a period of high traffic, the remaining hosts became overloaded, leading to connection exhaustion and some failures for SSH-based operations. Additional capacity was provisioned to expand SSH capacity and resolve the incident. The expanded capacity was fully online by 18:18 UTC. To reduce the likelihood of similar incidents, we will implement faster scaling solutions for SSH infrastructure and improved alerting for host availability and capacity thresholds.
On May 5, 2026, from approximately 13:22 UTC to 17:05 UTC, GitHub Actions hosted runners in the East US region were degraded. 13.5% of jobs requesting a standard runner failed and ~16% of requested Larger Runners with private networking pinned to East US failed or were delayed by more than 5 minutes. Copilot Code Review requests were also impacted. Approximately 8,500 code review requests timed out during this window. Affected users saw an error comment on their pull requests and were able to retry by re-requesting a review. Most runner requests were picked up by other regions automatically, but a portion of requests still routing to East US were impacted.This was triggered by a scale-up operation for hosted runner VMs in the East US region. This is a regular operation, but the VM create load hit an internal rate limit when VM creates pull images from storage. Existing backoff logic was not triggered because of the response code returned in this case. The rate limiting and VM creation failures were mitigated by reducing load to allow for recovery and allowing queued work to be processed. By 15:34 UTC, queued and failed job assignments were mostly mitigated, with less than 0.5% of runner assignments impacted between 15:34 and full recovery at 17:05.We are improving our system’s throttling behavior when limits occur, improving our controls to more quickly mitigate similar situations in the future, and reviewing all limits end-to-end for similar operations. We also immediately paused all scale and similar operations until these changes are in place and validated.
On 2026-05-04 at 3:37:17 PM UTC we detected increased latency on issues resulting in timeouts, and elevated 500 errors on webhooks. A scheduled workload drove high utilization on the primary host of a critical datastore, saturating the connection pool. We paused the job to mitigate the problem at 4:40:05 PM UTC and have implemented measures to prevent recurrence.
On April 28, 2026, at approximately 14:07 UTC, GitHub received reports that pull requests were missing from search results across global and repository /pulls pages. The issue was caused by a manually invoked repair job intended for a single repository, which was executed without the required safety flags. During execution of the repair job, the database query remained correctly scoped to the repo’s PR IDs. However, the Elasticsearch reconciliation logic did not apply the same scope. It interpreted the min and max PR IDs as a continuous range, causing unrelated PR documents across other repos to be marked for deletion. This resulted in the removal of 1,789,756,838 PR documents from the search index, approximately 49% of indexed PR documents. Customer impact was limited to PR search and list discoverability. Primary storage was unaffected, and there was no impact to opening, updating, or merging PRs. The issue was identified ~10 minutes after initial customer reports. Because it affected search index completeness rather than service availability, it was not caught by existing monitoring. The root cause was a flaw in the search document repair framework: it allowed a scoped reconciliation to run without enforcing a matching Elasticsearch query scope. This created a destructive mismatch between the source-of-truth and the index. The issue was compounded by the ability to trigger the job from the production console without safety defaults. Prior testing focused only on safe backfill scenarios and did not cover this reconciliation path. Additionally, there was no automated detection for large-volume deletions in Elasticsearch. We mitigated the incident through three parallel actions: (1) Deployed a MySQL-backed search fallback for the most active repos by traffic to restore PR visibility for highly impacted users (2) Initiated a snapshot restore and reindex process to repopulate missing pull request documents in Elasticsearch (3) Added a degradation notice on PR pages to inform users of incomplete search results while recovery was in progress. The incident was resolved on May 1, 2026 at 4:15 UTC, following completion and validation of the reindex process. To prevent recurrence, we are prioritizing improvements to the repair framework and safeguards. These include enforcing scoped query alignment between primary storage and Elasticsearch, preventing destructive operations without explicit opt-in, strengthening guardrails for manual repair jobs, and evaluating restrictions on production console access. In parallel, we are expanding automated test coverage for reconciliation safety invariants and introducing detection for anomalous deletion patterns in Elasticsearch so similar issues can be identified or blocked earlier. We are committed to improving the safety and reliability of our repair systems and ensuring that operational workflows are resilient to both software defects and manual invocation risks.