How to Fix InsufficientInstanceCapacity Error in AWS EC2
Suppose AWS doesn't currently have enough available On-Demand capacity to complete your request. In that case, you may encounter the InsufficientInstanceCapacity error when you try to launch a new instance or restart a stopped instance.
Resolution Steps
1. Wait and Retry
AWS capacity can shift frequently. If you encounter this error, wait and then submit your request again.
2. Change the Instance Type
If waiting does not resolve the issue, try changing the instance type:
Navigate to Actions > Instance Settings > Change Instance Type.
Select the desired instance type.
Note: Ensure you take a backup of the instance before making changes.
3. Move the Instance
If changing the instance type does not work, move the instance to another VPC, subnet, or Availability Zone.
Avoiding Insufficient Capacity Errors on Critical Machines
To ensure that critical machines are not affected by capacity issues, consider creating On-Demand Capacity Reservations in advance.
Steps to Use On-Demand Capacity Reservations:
Create the Capacity Reservation in a specific Availability Zone. Follow the official AWS guide here.
Launch critical instances into the Capacity Reservation. Refer to the AWS guide on launching instances into Capacity Reservations.
Monitor usage in real-time and launch instances into it as needed.
For a comprehensive understanding of Capacity Reservations, visit the AWS EC2 Capacity Reservations documentation.
Note: Be aware that charges are associated with Capacity Reservations. They are billed at the equivalent On-Demand rate, whether the reserved capacity is utilized or not. If the reservation remains unused, it will appear as an unused reservation on your Amazon EC2 bill.
For more details, refer to the official AWS documentation on Capacity Reservations Pricing.
