ImportError: cannot import name 'declarative_base' from 'sqlalchemy.ext.declarative'

How to fix ImportError: cannot import name 'declarative_base' from 'sqlalchemy.ext.declarative'

SQLAlchemy 2.0 removed sqlalchemy.ext.declarative.declarative_base. Import it from sqlalchemy.orm instead: from sqlalchemy.orm import declarative_base. (Or go full 2.0 style with class Base(DeclarativeBase).) One-line change, same behavior.

The exact error

ImportError: cannot import name 'declarative_base' from 'sqlalchemy.ext.declarative'

Fix it

1. Replace from sqlalchemy.ext.declarative import declarative_base with from sqlalchemy.orm import declarative_base.

Expected: import works on SQLAlchemy 2.x

1. Run your test suite and migrations.

Expected: models load, migrations run

1. Optional modernize: from sqlalchemy.orm import DeclarativeBase and class Base(DeclarativeBase): pass.

Expected: 2.0-native style

When this applies

SQLAlchemy 2.x and old sqlalchemy.ext.declarative imports

When this does NOT apply

SQLAlchemy 1.4 (both import paths work there)

Versions

SQLAlchemy >= 2.0

Why it happens

1.4 deprecated the ext.declarative location; 2.0 removed it.

Edge cases

Some old tutorials also use sqlalchemy.ext.declarative.api; same fix.