# X_MIGRATION_CONFLICT

## Means

the migration ledger disagrees with this build

## Typical cause

a ledger row from an app version this build does not ship, an applied migration whose file was edited so its checksum moved, or a rollback aimed at a row whose `down` SQL exists only in the build that shipped it. The wiki used to name `x db status --json` here; that command has never existed — the `db` subcommands are `gen`, `migrate`, `reset`, `studio`, `branch` and `backfill` — and this is one of the two errors most likely to fire during a real deploy. **One narrow exception is not a conflict** (`As of 2026-10-05`): when every unknown ledger row sorts after the newest migration the build ships, and the build has no migration left to apply, the migrator reads it as a rollback onto a newer build's schema — it applies nothing, logs `ultimate migrate ledger ahead of build` and returns the ids as `ahead`. Every other rollback state is still `X_MIGRATION_CONFLICT`: an unknown row between shipped migrations, a shipped migration this database never applied, or a build that ships no migrations at all

## Fix

the `fix` branches on which half disagreed. Foreign ledger row: deploy the app version `cause` names, or drop its row — `psql "$DATABASE_URL" -c "delete from x_migrations where id = '<id>'"`. Moved checksum: `git log -- packages/db/migrations/<id>.sql`, then `git checkout <rev> -- …` the revision whose checksum the ledger names (a committed edit is what HEAD holds), never edit an applied migration, then `x db gen "<change>"`. `x db gen` alone exits 0 and writes the edit into the schema dump. Unknown `down`: read the ledger with `psql "$DATABASE_URL" -c "select id, app_version from x_migrations order by id desc limit 5"` and roll back on the build that shipped it

[Entity and database](/error-codes#entity-and-database)