TerraformPilot

Troubleshooting

Fix Terraform Lambda Function - InvalidParameterValueException

Fix AWS Lambda InvalidParameterValueException in Terraform. Covers runtime versions, handler paths, IAM role ARN, package size, VPC config, and layer ARNs.

LLuca Berton2 min read

Quick Answer

#

A Lambda configuration parameter is invalid — wrong runtime, incorrect handler path, missing IAM role, oversized deployment package, or misconfigured VPC settings. Check the specific detail in the error message.

The Error

# 
Error: creating Lambda Function (my-function):
  InvalidParameterValueException: The runtime parameter of nodejs14.x
  is no longer supported.
Error: creating Lambda Function:
  InvalidParameterValueException: The role defined for the function
  cannot be assumed by Lambda.
Error: creating Lambda Function:
  InvalidParameterValueException: Unzipped size must be smaller
  than 262144000 bytes.

What Causes This Error

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1. Deprecated Runtime

#

AWS regularly deprecates Lambda runtimes. Check supported runtimes.

2. Wrong IAM Role Configuration

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The role's trust policy doesn't allow Lambda to assume it, or the role doesn't exist.

3. Handler Path Mismatch

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The handler doesn't match the file structure in the deployment package.

4. Package Too Large

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Unzipped deployment package exceeds 250 MB, or the zipped package exceeds 50 MB for direct upload.

5. VPC Configuration Issues

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Missing subnet IDs, security group IDs, or insufficient ENI permissions.

How to Fix It

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Solution 1: Use a Supported Runtime

# 
resource "aws_lambda_function" "main" {
  function_name = "${var.project}-${var.environment}-processor"
  role          = aws_iam_role.lambda.arn
  handler       = "index.handler"
  runtime       = "nodejs20.x"  # Use current runtime
  filename      = data.archive_file.lambda.output_path
 
  source_code_hash = data.archive_file.lambda.output_base64sha256
}

Current supported runtimes (2025):

LanguageRuntime
Node.jsnodejs20.x, nodejs22.x
Pythonpython3.11, python3.12, python3.13
Javajava17, java21
.NETdotnet8
Goprovided.al2023 (custom runtime)
Rubyruby3.3

Solution 2: Fix IAM Role Trust Policy

# 
resource "aws_iam_role" "lambda" {
  name = "${var.project}-lambda-role"
 
  assume_role_policy = jsonencode({
    Version = "2012-10-17"
    Statement = [{
      Effect    = "Allow"
      Principal = { Service = "lambda.amazonaws.com" }
      Action    = "sts:AssumeRole"
    }]
  })
}
 
resource "aws_iam_role_policy_attachment" "lambda_basic" {
  role       = aws_iam_role.lambda.name
  policy_arn = "arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole"
}
 
# For VPC-attached Lambda
resource "aws_iam_role_policy_attachment" "lambda_vpc" {
  role       = aws_iam_role.lambda.name
  policy_arn = "arn:aws:iam::aws:policy/service-role/AWSLambdaVPCAccessExecutionRole"
}

Solution 3: Fix Handler Path

# 
# Handler format: filename.function_name (without extension)
# Python: app.handler → app.py → def handler(event, context)
# Node.js: index.handler → index.js → exports.handler
 
resource "aws_lambda_function" "main" {
  handler = "src/app.handler"  # File: src/app.py, Function: handler
  # OR
  handler = "index.handler"    # File: index.js, Function: handler
}

Solution 4: Fix Package Size

# 
# For large packages, use S3 instead of direct upload
resource "aws_s3_object" "lambda_package" {
  bucket = aws_s3_bucket.deploy.id
  key    = "lambda/${var.project}.zip"
  source = data.archive_file.lambda.output_path
  etag   = filemd5(data.archive_file.lambda.output_path)
}
 
resource "aws_lambda_function" "main" {
  function_name = var.project
  s3_bucket     = aws_s3_bucket.deploy.id
  s3_key        = aws_s3_object.lambda_package.key
  handler       = "index.handler"
  runtime       = "python3.12"
  role          = aws_iam_role.lambda.arn
 
  # Use layers for large dependencies
  layers = [aws_lambda_layer_version.dependencies.arn]
}

Troubleshooting Checklist

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  1. ✅ Is the runtime supported? (Check AWS docs for current runtimes)
  2. ✅ Does the IAM role trust policy allow lambda.amazonaws.com?
  3. ✅ Does the handler path match the file in the ZIP?
  4. ✅ Is the package under 250 MB unzipped / 50 MB zipped?
  5. ✅ For VPC Lambda: are subnet IDs and security groups valid?
  6. ✅ Do Lambda layers exist and have compatible runtimes?

Prevention Tips

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  • Check runtime deprecation dates — plan upgrades before cutoff
  • Use S3 for deployment packages — avoids the 50 MB direct upload limit
  • Use layers for dependencies — keeps the function package small
  • Test handler paths locally — sam local invoke or similar
  • Add VPC execution role when using vpc_config
#

Conclusion

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Lambda InvalidParameterValueException means a configuration value is wrong. Check the specific detail — deprecated runtime, wrong handler path, oversized package, or IAM role issues. Use current runtimes, validate handler paths, and use S3 + layers for large deployments.

#Terraform#AWS#Troubleshooting#Error Fix

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