Overview
This advisory addresses the October 20, 2025 AWS service event in US-EAST-1, helping customers understand cost implications, identify usage anomalies, and navigate the SLA credit process.
What Happened
On October 20, 2025, from 3:00 AM to 6:00 PM ET, AWS experienced intermittent service degradation in the US-EAST-1 region. A DNS resolution failure impacted EC2, Lambda, load balancers, and API Gateway. AWS restored stability later that day after identifying and remediating the underlying issue.
How This Affects Cloud Costs
1. Charges for Limited-Use Services
Resources continued running without serving traffic during the disruption. Idle databases and disconnected EC2 instances still generated charges with minimal business value returned.
2. Retry Storm Cost Spikes
Automatic retry mechanisms created artificial cost increases through Lambda timeouts and re-executions, API Gateway request multiplication, data transfer overages, and CloudWatch log surges.
3. Failover and Recovery Costs
Cross-region disaster recovery triggered unexpected charges for data transfer, resource scaling, and backup restoration.
What to Look For
When analyzing your cost data, distinguish between:
- Event-driven spikes: Lambda invocations and API calls from retry loops
- Idle resource charges: Metering on unavailable services during the outage window
- Legitimate business activity: Normal workload costs outside the event window
Affected customers typically report 5-20x baseline usage levels during the incident period.
Next Steps
Step 1: Document Your Impact (This Week)
- Identify US-EAST-1 resources via AWS Cost Explorer
- Export hourly costs for October 20 (3:00 AM - 6:00 PM ET)
- Capture CloudWatch error metrics and timeout data
- Calculate event costs versus normal operations
Step 2: File Your SLA Credit Claim
Critical deadline: December 31, 2025 (within two billing cycles).
Open an AWS Support Center case referencing the October 20 incident. Include dates, affected resources, and error logs demonstrating unavailability. Expected credits align with approximately 98% uptime, potentially qualifying for a 10% service credit on impacted workloads.
Step 3: Recover Beyond-SLA Costs
Lambda retry overages, data transfer spikes, API Gateway cost explosions, and cross-region failover expenses require separate AWS Support tickets referencing the October 20 incident with cost comparisons.
Step 4: Verify Credits Applied
Monitor your next billing cycle for credit reflection. Reopen support cases if credits do not appear.
Key Takeaways
- File SLA claims by December 31, 2025 -- this is a non-negotiable deadline
- Standard SLA provides 10% credit on affected compute resources
- Retry storms require separate escalated claims
- Document impact immediately for better log accessibility
- Multi-region architectures qualify for superior SLA commitments (99.99% versus 99.5%)
Contact
For further assistance analyzing outage-related cost anomalies, reach out to PointFive at [email protected] or visit pointfive.co/contact.