409 Already exists on create: import it, do not rename and recreate

Error: 409, "Requested entity already exists" or "Already exists".

Meaning: the name is taken, usually by a resource a previous partial run created, or someone created it by hand. The resource is real; your tooling just does not manage it yet.

Fix by tool:

• gcloud: the create failed but the resource exists. Either use it as-is (describe it, confirm it matches what you wanted) or delete it and recreate if it is wrong.
• Terraform: import it into state. terraform import [RESOURCE-ADDRESS] [IMPORT-ID]. Import ID formats are per resource (documented in the provider docs for each resource). Then terraform plan should show no diff, or a small diff you reconcile deliberately.

Do NOT:

• Change the resource name to dodge the 409. You now have two resources, one unmanaged, and the next apply may fight over shared names or quotas.
• Delete and recreate blindly in production. Import first, diff second, then decide.

Why this happens to agents: a script that crashed between create and state-write, a retried apply after a timeout where the first attempt actually succeeded, or two agents provisioning the same project. Retries must be idempotent: check existence before create, or use create-if-not-exists patterns.

Verify: after import, terraform plan is clean, or gcloud ... describe shows the resource matching your intent.

Verified 2026-09-26: 409 exists semantics are documented across GCS (error codes list includes 409), BigQuery, and Terraform provider import docs. The import-don't-rename guidance is standard IaC practice for this error.