Table of Contents

The Error

Error creating Lambda Function: InvalidParameterValueException

What Causes This

Lambda creation fails due to invalid configuration. Common causes: wrong handler format, unsupported runtime, deployment package too large (50MB zipped / 250MB unzipped), IAM role not yet propagated, or VPC configuration issues.

How to Fix It

Solution 1: Fix Handler Format

# Handler format: filename.function_name (without extension)
resource "aws_lambda_function" "api" {
  filename      = "lambda.zip"
  function_name = "my-api"
  role          = aws_iam_role.lambda.arn

  # Python: file_name.function_name
  handler = "main.handler"         # main.py → def handler(event, context)

  # Node.js: file_name.export_name
  # handler = "index.handler"      # index.js → exports.handler

  # Go: bootstrap (for provided.al2023 runtime)
  # handler = "bootstrap"

  runtime = "python3.12"
}

Solution 2: Wait for IAM Role Propagation

resource "aws_iam_role" "lambda" {
  name = "lambda-role"
  assume_role_policy = jsonencode({
    Version = "2012-10-17"
    Statement = [{
      Action = "sts:AssumeRole"
      Effect = "Allow"
      Principal = { Service = "lambda.amazonaws.com" }
    }]
  })
}

# Add a delay for IAM propagation
resource "time_sleep" "wait_for_iam" {
  depends_on      = [aws_iam_role.lambda]
  create_duration = "10s"
}

resource "aws_lambda_function" "api" {
  depends_on    = [time_sleep.wait_for_iam]
  function_name = "my-api"
  role          = aws_iam_role.lambda.arn
  handler       = "main.handler"
  runtime       = "python3.12"
  filename      = "lambda.zip"
}

Solution 3: Check Package Size

# Check zip size (max 50MB for direct upload)
ls -lh lambda.zip

# If too large, use S3
aws s3 cp lambda.zip s3://my-deployments/lambda.zip

resource "aws_lambda_function" "api" {
  s3_bucket     = "my-deployments"
  s3_key        = "lambda.zip"
  function_name = "my-api"
  role          = aws_iam_role.lambda.arn
  handler       = "main.handler"
  runtime       = "python3.12"
}

Prevention Tips

  1. Pin provider versions — avoid surprise breaking changes
  2. Use CI/CD — catch errors before they hit production
  3. Test with terraform plan — always review before applying
  4. Keep Terraform updated — newer versions have better error messages
  5. Use terraform validate — catches syntax errors early

Hands-On Courses

Learn to avoid these errors with interactive, project-based courses:

Conclusion

This error is common and fixable. Follow the solutions above, and check our Terraform course for hands-on training that covers real-world troubleshooting scenarios.