Error: Failed to install provider
Error: Failed to query available provider packages
Error: Backend initialization required, please run "terraform init"

terraform init downloads providers and configures the backend. When it fails, nothing else works.

Fix 1: Network / Proxy Issues

# ❌ Can't reach registry.terraform.io
# ✅ Check connectivity
curl -I https://registry.terraform.io

# Behind a proxy:
export HTTP_PROXY=http://proxy:8080
export HTTPS_PROXY=http://proxy:8080
terraform init

Fix 2: Provider Version Conflict

# ❌ Required version doesn't exist
terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "= 99.0.0"  # 💥 Doesn't exist
    }
  }
}

# ✅ Use a valid version constraint
version = "~> 5.0"

Fix 3: Clear Plugin Cache

# ❌ Corrupted cache
# ✅ Remove and re-download
rm -rf .terraform
rm .terraform.lock.hcl
terraform init

Fix 4: Backend Configuration Changed

# ❌ Backend config changed but not re-initialized
# ✅ Re-init with migration
terraform init -migrate-state

# Or reconfigure
terraform init -reconfigure

Fix 5: Wrong Terraform Version

# Check version
terraform version

# If provider requires newer Terraform:
# Install the required version
# Or use tfenv/tfswitch
tfenv install 1.7.0
tfenv use 1.7.0

Fix 6: S3 Backend Access Denied

# ❌ Can't access state bucket
# ✅ Check AWS credentials
aws sts get-caller-identity
aws s3 ls s3://my-terraform-state/

# Check bucket policy and IAM permissions

Related resources

• Terraform cheat sheet
• Terraform provider not found fix
• Terraform state lock fix