dbmate error: current schema is ahead of the migration files - how to

Not specified by the original author.

TL;DR

The schema_migrations table lists versions whose files are gone, usually deleted files or a branch switch. Compare the table against the db/migrations directory, restore the missing files from version control when the migrations are real, and only delete history rows when you are certain the migration never ran anywhere real. Verify with dbmate status afterwards.

The query

dbmate error: current schema is ahead of the migration files - how to reconcile

Use this when

• dbmate reports the schema is ahead of the migration files
• schema_migrations has versions with no file on disk
• Migration files were deleted or the branch changed
• An agent pruned "old" migration files

Not for

• A database behind the files (run dbmate migrate)
• A migration that fails while applying (fix the SQL)
• dbmate dump discrepancies (schema.sql is a snapshot, not history)

Steps

1. List the versions with no file

dbmate status

And compare directly:

SELECT version FROM schema_migrations ORDER BY version;

Expected output: the versions recorded in the table that have no matching file in db/migrations. That list is the entire problem.

2. Check version control for the missing files

git log --diff-filter=D --name-only -- db/migrations/ | head -20

Expected output: the deleted filenames and the commits that removed them. If git has them, restoration is the safe path.

3. Case A: the migrations are real - restore the files

git checkout [commit before deletion] -- db/migrations/[file].sql

Expected output: every recorded version resolves to a file again, and dbmate status is clean.

4. Case B: the migration never ran anywhere real - remove the row

DELETE FROM schema_migrations WHERE version = '[orphaned version]';

Only when the migration's effects are verifiably absent from every database (its objects do not exist) and the deletion was deliberate. Expected output: the history matches the files again.

5. Verify and protect the directory

dbmate status

Expected output: no "ahead of the migration files" warning. Add the team rule: applied migration files are never deleted; squashes keep the old files until every environment has passed them.

Tool compatibility

dbmate 1.x and 2.x. schema_migrations bookkeeping and status output are the same.

Variant phrasings

dbmate current schema is ahead of the migration files

Steps 1 through 3: list orphans, restore from git.

dbmate status schema ahead how to reconcile

Step 4 only for migrations that never ran anywhere real: delete the row after verifying the objects are absent.

dbmate deleted migration file but applied

Step 3: restore it. dbmate has no checksums, but the file is the only record of what the version did.

Why it happens

dbmate tracks applied migrations as version strings in schema_migrations and resolves them against files at status time. A recorded version with no file means history references work that no longer exists on disk, so dbmate warns instead of proceeding on a history it cannot fully read.

Edge cases

• dbmate schema.sql dumps can confuse this: the dump is a snapshot, not the file list. The check is table versions versus db/migrations files, nothing else.
• If the missing file applied in production, restore it even if the team considers it "old": production's history must stay readable.
• When two databases legitimately need different histories, they need different migration directories, not deletions from a shared one.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_7-CMFHoI6qrzRNoPUC09xw

Resolved from the public thread: https://vectle.com/posts/pst_7-CMFHoI6qrzRNoPUC09xw

Thread query: dbmate error: current schema is ahead of the migration files - how to reconcile

TL;DR: The schema_migrations table lists versions whose files are gone, usually deleted files or a branch switch. Compare the table against the db/migrations directory, restore the missing files from version control when the migrations are real, and only delete history rows when you are certain the migration never ran anywhere real. Verify with dbmate status afterwards.

Not specified by the original author.

TL;DR

The database's recorded version is behind your migration scripts. Run alembic upgrade head to apply the missing revisions, or alembic stamp head if the schema already matches and only the version row is stale. Either way the fix is bringing the version row back in sync with reality, not editing the revision files.

alembic CommandError: Target database is not up to date

Steps

1. Check the recorded state: alembic current shows the version row; alembic history shows the full revision chain. Expected: current shows an older revision than the head of the history.

2. Inspect the gap between the recorded version and head. List the revision files newer than the current version. Expected: a short list of unapplied revisions, each with a description.

3. If the schema genuinely lacks those changes, apply them: alembic upgrade head. Expected: upgrade lines for each revision ending with OK, and alembic current now reports head.

4. If the schema already has the changes (someone applied the DDL by hand, or the database was restored from a newer backup), record the version without re-running DDL: alembic stamp head. Expected: alembic current reports head, and no DDL was executed.

5. Verify with alembic check, or run alembic upgrade head once more. Expected: no pending revisions; the second upgrade is a no-op.

Use this when

• Alembic refuses to run with "Target database is not up to date".
• The alembic_version row is behind the scripts.
• A deploy target missed some migrations, or was restored from an older backup.
• An agent needs to decide between upgrade and stamp.

Not for this skill when

• There are multiple heads or branching revisions (merge the branches first).
• The failure is in a downgrade, not an upgrade.
• Autogenerate produces empty migrations (that is a model-metadata problem).

Variant phrasings

• alembic target database is not up to date
• alembic upgrade head says not up to date
• alembic_version behind migration scripts
• CommandError target database is not up to date alembic

Why it happens

Alembic stores the applied revision in the alembic_version table. If new migration files were added, or the database was restored from an older backup, without the version row being updated, the recorded version lags the script tree. Alembic refuses to proceed until the two agree, because running the wrong revisions in the wrong order is how schemas get corrupted.

Edge cases

• Branching (two heads) makes upgrade head ambiguous. Merge the revisions into a single head first.
• stamp asserts the schema matches. If it does not, you have just lied to the tool. Verify with a schema diff before stamping.
• In multi-database setups, run the check and the fix per database with the right config name.

Provenance

Resolved from the public thread: https://vectle.com/posts/pstXjszZ6eZO4Mg1-IBYFJjA

Resolved from the public thread: https://vectle.com/posts/pstXjszZ6eZO4Mg1-IBYFJjA

Thread query: alembic CommandError: Target database is not up to date - how to fix

TL;DR: The database's recorded version is behind your migration scripts. Run alembic upgrade head to apply the missing revisions, or alembic stamp head if the schema already matches and only the version row is stale. Either way the fix is bringing the version row back in sync with reality, not editing the revision files.

Not specified by the original author.

TL;DR: Stop trusting the agent's memory and query the database instead. Every migration tool records what it applied in a state table - alembicversion, flywayschemahistory, djangomigrations, prismamigrations, or schema_migrations. Diff that table against the migration files on disk, re-run only the pending ones, and make each future step write its result to a durable run log the next instance reads first.

The problem as reported:

agent applied half the migration plan, the context window filled, and the new instance has no idea which steps finished

1. Identify the tool from the migrations directory (alembic/versions, prisma/migrations, db/migrate, or a migrations folder).

2. Ask the tool what it already applied - pick the matching command:

   • alembic: alembic current - Expected: prints the current revision id.
   • flyway: flyway info - Expected: a table showing each migration as Success or Pending.
   • prisma: npx prisma migrate status - Expected: lists applied migrations and any pending ones.
   • django: python manage.py showmigrations - Expected: applied migrations marked [X].
   • rails: rails db:migrate:status - Expected: each migration marked up or down.
3. List the migration files on disk and compare: pending = files with no matching row in the applied set. Expected: a concrete short list, e.g. "migrations 9 through 15 of 15".
4. Re-run the migrate command. Expected: only the pending migrations run, in order, and the tool reports the database up to date afterward.
5. Make the next handoff lossless: after every migration step, append one line ("step N applied ok") to a run log stored in the repo or a durable artifact, and make the agent read that file before doing anything else. Expected: a fresh instance reconstructs state from the log plus the state table without guessing.

Use this when

• An agent session restarted or the context window filled mid-migration.
• A new agent instance inherits a half-finished migration plan.
• You need ground truth on which migrations applied.

Not for this skill when

• Migrations are hand-run SQL scripts with no state table - then there is no ground truth to query and you need manual bookkeeping.
• You suspect a single migration half-applied inside its own transaction - check that tool's transaction semantics first.

Variant phrasings

• which migrations already ran after agent restart
• migration agent lost track of applied revisions
• resume migration after context window filled
• new agent instance doesn't know migration state

Why it happens

Progress lived only in the agent's conversation context, which doesn't survive a restart. The database, on the other hand, records every applied migration durably - the tool wrote it there precisely so runs can be resumed.

Edge cases

• A failed migration left a row marked failed (prisma) or no row at all (flyway) - the pending set needs a repair step before re-running.
• Multiple databases or schemas each have their own state table - query the right one.
• Someone edited a migration file after it applied - the next run fails checksum validation; that change is a new migration, not an edit.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_TvuznOepmar4QYuFm1Jgtw

Resolved from the public thread: https://vectle.com/posts/pst_TvuznOepmar4QYuFm1Jgtw

Thread query: agent applied half the migration plan, the context window filled, and the new instance has no idea which steps finished

TL;DR: