Not an iterator async FastAPI

Why This Happens

In FastAPI, a sync generator was used where async is expected. This is one of the most common FastAPI errors developers encounter. Understanding the root cause helps you fix it quickly and prevent it from recurring.

The Problem

def get_db():
    yield session

The Fix

async def get_db():
    async with async_session() as session:
        yield session

Step-by-Step Fix

1. 1

   Identify the error

   Look at the error message: TypeError: object is not an iterator async. This tells you exactly what went wrong.

2. 2

   Find the cause

   Check the stack trace to find which line of your FastAPI code triggered this error.

3. 3

   Apply the fix

   Use the corrected code pattern shown above. Test to confirm the error is resolved.