Table of Contents

The Error

When working with Terraform, you may encounter this error:

Error: Duplicate resource aws_instance configuration

This error can block your entire workflow. Let’s understand why it happens and how to fix it.

What Causes This Error

Two resource blocks with identical type and name exist in the configuration, possibly across different .tf files.

How to Fix It

Solution 1

Rename one of the duplicate resources to a unique name.

Solution 2

Search across all .tf files: grep -r ‘resource aws_instance example’ .

Solution 3

If they should be one resource, merge the configurations and remove the duplicate.

Solution 4

Use for_each or count if you need multiple instances of the same resource type.

Prevention Tips

  • Always run terraform validate before terraform plan
  • Use terraform fmt to keep configuration clean and readable
  • Pin provider versions to avoid unexpected schema changes
  • Review plan output carefully before applying

Learn More

Conclusion

This error is common but straightforward to fix. The key is understanding the root cause and applying the correct solution for your specific situation. Following the prevention tips above will help you avoid this error in future projects.