How to fix Error: Provider alias not found in Terraform

Check your root module (usually main.tf or providers.tf) to ensure all referenced aliases are actually defined.

Example of correct provider alias definition:

# Root module - main.tf
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

provider "aws" {
  region = "us-east-1"
}

provider "aws" {
  alias  = "replica"
  region = "us-west-2"
}

If you're missing a provider alias definition that your configuration needs, add it to your root module.

If you're using modules with aliased providers, ensure you're passing providers explicitly to the module.

module "app_replica" {
  source = "./modules/app"

  # Explicitly pass the aliased provider to the module
  providers = {
    aws = aws.replica
  }
}

Without the providers argument, the module receives only the default provider configuration.

If you have a child module that uses aliased providers, declare them using configuration_aliases in the required_providers block.

# modules/app/main.tf
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
      configuration_aliases = [aws.replica]
    }
  }
}

resource "aws_s3_bucket" "backup" {
  provider = aws.replica
  bucket   = "my-backup-bucket"
}

This tells Terraform and other developers that this module accepts an aliased provider.

If you removed a provider alias from your configuration but resources still reference it in state, you have two options:

Option 1: Temporarily restore the provider to destroy resources

# Restore the provider alias
provider "aws" {
  alias  = "old_region"
  region = "deprecated-region"
}

# Resources will reference it, allowing terraform destroy

Then run:

terraform destroy -target='aws_resource.name'

Option 2: Manually remove from state (advanced)

terraform state rm 'aws_resource.name'

This is a last resort if you cannot restore the provider configuration.

After making changes, validate that your configuration is correct:

terraform validate

This will catch issues like:
- Undefined provider aliases
- Incorrect module provider references
- Missing configuration_aliases declarations

If terraform validate succeeds, you can proceed with terraform plan.