Updating Django migrations in place

Published 2 April, 2026.

Today I learned about the --update option in Django’s makemigrations command.

From Django’s documentation:

Merges model changes into the latest migration and optimize the resulting operations.

The updated migration will have a generated name. In order to preserve the previous name, set it using --name.

I’ve got no idea how long this option has existed, but I’ve already found it helpful in reducing the amount of migration wrangling I’ve needed to do manually.

Using the –name option

The --name option is a bit fiddly; it’ll take whatever name you provide and prefix it with a migration number, but will also suffix the name with “_update”.

For example, --name my_migration will create a migration file named 0002_my_migration_update.py.

It handles RunPython operations … sort of

If the migration you’re updating contains any RunPython operations, it will preserve them, but it won’t copy the code for you.

In the new updated migration, your RunPython operation will look like this:

migrations.RunPython(
    code=my_app.migrations.0002_my_migration.do_thing,
),

…and the following comment is injected into the file:

# Functions from the following migrations need manual copying.
# Move them and any dependencies into this file, then update the
# RunPython operations to refer to the local versions:
# my_app.migrations.0002_my_migration

I suspect this is the reason the new migration is created with the _updated suffix; the existing migration needs to be left untouched so that the user can copy over functions.

I suspect other operations are handled similarly, but I haven’t tested them.

Can only update “leaf” migrations

Unfortunately, --update can’t apply changes to a migration that another migration relies on.

❯ ./manage.py makemigrations --update
CommandError: Cannot update migration 'new_thing.0001_initial' that migrations 'other_thing.0002_changes_on_top_of_new_thing' depend on.

This is fair enough—Django can’t know if updates to new_thing.0001_initial will have any flow-on effects to other_thing.0002_changes_on_top_of_new_thing.