Terraform "Backend configuration changed" in CI

Terraform detected that the current backend configuration does not match the one recorded in .terraform. It stops and asks you to run init with -reconfigure (ignore old state) or -migrate-state (move state) before it proceeds.

What this error means

terraform init stops with "Error: Backend configuration changed" and "A change in the backend configuration has been detected ... run \"terraform init\" with the \"-reconfigure\" or \"-migrate-state\" flags".

Error: Backend configuration changed

A change in the backend configuration has been detected, which may require
migrating existing state.

If you wish to attempt automatic migration of the state, use "terraform init
-migrate-state". If you wish to store the current configuration with no changes
to the state, use "terraform init -reconfigure".

Common causes

The backend block or -backend-config values changed

A bucket, key, region, or other backend setting differs from what init previously recorded, so Terraform will not silently switch backends.

A stale .terraform from a different backend

A cache restored .terraform initialized against a different backend than the current config declares.

How to fix it

Reconfigure when the change is intentional and state stays put

1. If you are pointing at a backend that already holds the right state, init with -reconfigure.
2. Pass the same -backend-config values the config expects.
3. Re-run plan against the reconfigured backend.

terraform init -reconfigure -input=false -backend-config=backend.hcl

Migrate state when moving backends

To move existing state to a new backend, init with -migrate-state so Terraform copies it across.

terraform init -migrate-state -input=false

How to prevent it

• Keep -backend-config values stable across CI runs.
• Choose -reconfigure vs -migrate-state deliberately.
• Do not restore a .terraform from a different backend.

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