Terragrunt Troubleshooting Guide

Root.hcl Cannot Find env.hcl

Symptom: Error: Attempt to get attribute from null value in root.hcl

Cause: Root.hcl is trying to read env.hcl via find_in_parent_folders("env.hcl"), but env.hcl doesn’t exist at the root level.

Solution: Make root.hcl environment-agnostic:

# DON'T do this in root.hcl for multi-environment setups:
locals {
  env_vars = read_terragrunt_config(find_in_parent_folders("env.hcl"))  # FAILS
}

# DO use static values or get_env():
generate "provider" {
  path      = "provider.tf"
  if_exists = "overwrite_terragrunt"
  contents  = <<EOF
provider "aws" {
  region = "us-east-1"  # Or: get_env("AWS_REGION", "us-east-1")
}
EOF
}

Provider Conflict with Registry Modules

Symptom: Error: Duplicate required providers configuration

Solutions:

1. Remove conflicting generate block — Only generate provider "aws", not required_providers, when using registry modules:

   generate "provider" {
     path      = "provider.tf"
     if_exists = "overwrite_terragrunt"
     contents  = <<EOF
   provider "aws" {
     region = "us-east-1"
   }
   EOF
   }

2. Use if_exists = "skip" — Skip generation if the file already exists:

   generate "versions" {
     path      = "versions.tf"
     if_exists = "skip"
     contents  = "..."
   }

3. Clear cache if conflicts persist:

   rm -rf .terragrunt-cache && terragrunt init

Feature Flag Validation Errors

Symptom: Unknown variable; There is no variable named "local" in feature blocks

Cause: Feature flag defaults must be static values, not references to locals or variables.

Solution: Ensure defaults are static values (see Feature Flags section in SKILL.md).

Child Module Cannot Find env.hcl

Symptom: Error: Attempt to get attribute from null value in a child module

Cause: Child module is trying to read env.hcl but the file doesn’t exist in the environment directory.

Solution: Ensure env.hcl exists in the environment directory:

dev/
├── env.hcl              # MUST exist
└── vpc/
    └── terragrunt.hcl   # Calls find_in_parent_folders("env.hcl")