How to fix Error: Failed to install provider in Terraform

The most common cause is a lock file with incomplete checksums. Remove it and regenerate:

rm .terraform.lock.hcl
terraform init

If you need to support multiple platforms (macOS, Linux, Windows):

terraform providers lock -platform=linux_amd64 -platform=darwin_amd64 -platform=windows_amd64

This generates a lock file with all platform checksums.

Verify your required_providers block has correct, current namespace. Some providers changed namespaces:

terraform {
  required_providers {
    aws = {
      source  = "hashicorp/aws"      # Correct namespace
      version = "~> 5.0"
    }
  }
}

Look for deprecated references like:
- terraform-providers/aws → use hashicorp/aws
- databrickslabs/databricks → use databricks/databricks

Update all .tf files to use current provider namespaces.

Check that you can reach the Terraform Registry:

curl -I https://registry.terraform.io
wget --spider https://registry.terraform.io

If these fail, you have a network problem:
- Check your internet connection
- Verify firewall rules allow outbound HTTPS
- If behind a corporate proxy, configure Terraform to use it
- Check DNS resolution: nslookup registry.terraform.io

Delete the .terraform directory and reinitialize:

rm -rf .terraform
terraform init

This forces Terraform to re-download all providers fresh, which can fix corruption from interrupted downloads.

Ensure all team members use the same Terraform version:

terraform version

After upgrading Terraform (especially from 0.13 to 0.14+), regenerate the lock file:

rm .terraform.lock.hcl
terraform init

If upgrading caused the issue, also verify you don't have a state file from a newer Terraform version.

For third-party or custom providers, verify the binary exists:

terraform providers

This lists all required providers and their locations. If a provider is missing, check:
- Is the provider published to the registry?
- Is it available for your OS (linux_amd64, darwin_amd64, etc.)?
- For custom providers, is the plugin correctly placed in ~/.terraform.d/plugins/?