# CHECKSUM_MISMATCH

A migration file no longer matches the checksum `migrate:create` recorded in its snapshot.

## Cause

A migration file no longer matches the checksum `migrate:create` recorded in its snapshot.

`nextly migrate:create` records the checksum of each migration it writes in the file's snapshot. The file no longer matches it, so it was edited after it was generated, and its snapshot may no longer describe what it does.

## Fix

* Revert the edit, for example from version control.
* Or delete the file and re-generate it with `nextly migrate:create --name="<migration-name>"`.

See [Production migrations](https://nextlyhq.com/docs/guides/production-migrations.md).

## Example

```text
✗ The migration file `20261020_120000_add_posts.sql` was edited after generation.
  Why:  Expected SHA-256: 9f2c4e1a7b3d5f60812a4c6e8b0d2f4a6c8e0b2d4f6a8c0e2b4d6f8a0c2e4b6d
        Actual SHA-256:   3b5d7f9a1c3e5b7d9f1a3c5e7b9d1f3a5c7e9b1d3f5a7c9e1b3d5f7a9c1e3b5d
  Next: Either revert the edit, or delete this file and re-generate via `nextly migrate:create --name="<migration-name>"`.
  Docs: https://nextlyhq.com/docs/cli/errors/checksum-mismatch  (CHECKSUM_MISMATCH)
```