# InsufficientInstanceCapacity: We currently do not have sufficient capacity in the Availability Zone you requested

- **ID:** `aws/ec2-insufficient-instance-capacity`
- **Domain:** aws
- **Category:** resource_error
- **Error Code:** `InsufficientInstanceCapacity`
- **Verification:** ai_generated
- **Fix Rate:** 80%

## Root Cause

AWS EC2 fleet in the specified Availability Zone lacks available compute capacity for the requested instance type, often due to high demand or resource constraints.

## Version Compatibility

| Version | Status | Introduced | Deprecated |
|---------|--------|------------|------------|
| ec2-2024-01-01 | active | — | — |
| aws-cli/2.17.0 | active | — | — |

## Workarounds

1. **Change instance type to a similar but less popular one (e.g., from t3.medium to t3.large or t4g.medium) and relaunch.** (70% success)
   ```
   Change instance type to a similar but less popular one (e.g., from t3.medium to t3.large or t4g.medium) and relaunch.
   ```
2. **Use a different Availability Zone or enable 'No Preferred AZ' in Auto Scaling groups. For CLI: `aws ec2 run-instances --placement AvailabilityZone=us-east-1b`** (80% success)
   ```
   Use a different Availability Zone or enable 'No Preferred AZ' in Auto Scaling groups. For CLI: `aws ec2 run-instances --placement AvailabilityZone=us-east-1b`
   ```
3. **Use On-Demand Capacity Reservations or Savings Plans to reserve capacity in advance. Create a reservation: `aws ec2 create-capacity-reservation --instance-type t3.medium --availability-zone us-east-1a --instance-count 5`** (90% success)
   ```
   Use On-Demand Capacity Reservations or Savings Plans to reserve capacity in advance. Create a reservation: `aws ec2 create-capacity-reservation --instance-type t3.medium --availability-zone us-east-1a --instance-count 5`
   ```

## Dead Ends

- **Retry the same request repeatedly without changes** — AWS capacity is per-AZ and per-instance-type; retrying the same request won't allocate new capacity if it's exhausted across that AZ. (95% fail)
- **Increase the instance count in the same request expecting partial fulfillment** — The error is a hard capacity check; AWS rejects the entire launch request if any instance cannot be placed, not a partial fulfillment. (90% fail)