How to fix Error: Error creating ACM Certificate: LimitExceededException in Terraform

Log into your AWS Console and navigate to AWS Certificate Manager. Count how many certificates you currently have, or use the AWS CLI:

aws acm list-certificates --region us-east-1

This shows all certificates in the specified region. Note that ACM quotas are per-region per-account, so you'll need to check multiple regions if you use them.

Check if Terraform is trying to create duplicate certificates:

terraform state list | grep aws_acm_certificate

If the certificate already exists in state but you're getting an error, try:

terraform refresh

This updates your state file to match actual AWS resources. If the certificate exists in AWS but not in your Terraform state, import it:

terraform import aws_acm_certificate.example <certificate-arn>

Get the certificate ARN from the AWS Console under Certificate Manager.

If your error message says "Certificate has too many domains", you're hitting the per-certificate domain limit. Split your domains across multiple certificates:

Instead of:

resource "aws_acm_certificate" "main" {
  domain_name       = "example.com"
  subject_alternative_names = [
    "api.example.com",
    "app.example.com",
    "cdn.example.com",
    # ... many more domains
  ]
  validation_method = "DNS"
}

Use wildcards or split into multiple certificates:

resource "aws_acm_certificate" "main" {
  domain_name       = "example.com"
  subject_alternative_names = ["*.example.com"]
  validation_method = "DNS"
}

resource "aws_acm_certificate" "secondary" {
  domain_name       = "another.com"
  subject_alternative_names = ["*.another.com"]
  validation_method = "DNS"
}

If you legitimately need more certificates or domains, request a quota increase:

1. Go to AWS Service Quotas console: https://console.aws.amazon.com/servicequotas
2. Search for "Certificate Manager"
3. Find the quota you need to increase:
- "Number of certificates per account" (currently 2,500)
- "Domain names per ACM certificate" (currently 10, max 100)
4. Click on the quota, then "Request quota increase"
5. Enter your desired value
6. Submit the request

AWS typically approves quota increases within minutes to hours. You'll receive an email confirmation.

If you don't need an increase, free up quota by deleting unused certificates:

# List certificates in AWS Console or via CLI
aws acm list-certificates --region us-east-1

# Delete a specific certificate (via Console)
# Note: You cannot delete a certificate in use by other AWS services

Certificates deleted within the past 365 days still count against your yearly quota. If you're concerned about quota, requesting an increase is faster than waiting for the 365-day window to pass.

Once your quota increase is approved, retry your Terraform deployment:

terraform plan
terraform apply

If using CI/CD, ensure your pipeline has the latest AWS credentials with proper IAM permissions to create ACM certificates.