What causes "REMOTION_APP_REGION is not set" in remotion-dev/remotion?

Set REMOTION_APP_REGION in packages/lambda-python/.env (e.g. 'us-east-1').

remotion-dev/remotion · error · Exception

REMOTION_APP_REGION is not set

Error message

REMOTION_APP_REGION is not set

What it means

Raised by testclient_render_still.py when REMOTION_APP_REGION is unset after dotenv loading. Same guard as the render-media example: the still-render client cannot construct boto3 clients without an AWS region.

Source

Thrown at packages/lambda-python/testclient_render_still.py:13

import os

from remotion_lambda import RenderStillParams, Privacy, ValidStillImageFormats
from remotion_lambda import RemotionClient
from dotenv import load_dotenv


load_dotenv()

# Load env variables
REMOTION_APP_REGION = os.getenv('REMOTION_APP_REGION')
if not REMOTION_APP_REGION:
    raise Exception("REMOTION_APP_REGION is not set")

REMOTION_APP_FUNCTION_NAME = os.getenv('REMOTION_APP_FUNCTION_NAME')
if not REMOTION_APP_FUNCTION_NAME:
    raise Exception("REMOTION_APP_FUNCTION_NAME is not set")

REMOTION_APP_SERVE_URL = os.getenv('REMOTION_APP_SERVE_URL')
if not REMOTION_APP_SERVE_URL:
    raise Exception("REMOTION_APP_SERVE_URL is not set")

# Construct client
client = RemotionClient(region=REMOTION_APP_REGION,
                        serve_url=REMOTION_APP_SERVE_URL,
                        function_name=REMOTION_APP_FUNCTION_NAME)

# Set render still request
render_params = RenderStillParams(
    composition="still-helloworld",
    privacy=Privacy.PUBLIC,

View on GitHub (pinned to 78fe4bb3fd)

Solutions

Set REMOTION_APP_REGION in packages/lambda-python/.env (e.g. 'us-east-1').
Run the still example from packages/lambda-python so .env resolves.
Export inline: `REMOTION_APP_REGION=us-east-1 python testclient_render_still.py`.
Copy .env.example to .env and fill all three REMOTION_APP_* values.

Example fix

// before
REMOTION_APP_REGION=
// after
REMOTION_APP_REGION=us-east-1

Defensive patterns

Strategy: validation

Validate before calling

import os
from dotenv import load_dotenv
load_dotenv()
if not os.getenv('REMOTION_APP_REGION'):
    raise SystemExit('REMOTION_APP_REGION is not set')

Type guard

def has_region(v): return isinstance(v, str) and v.strip() != ''

Try / catch

try:
    assert os.getenv('REMOTION_APP_REGION')
except AssertionError:
    print('REMOTION_APP_REGION is not set'); sys.exit(1)

Prevention

Keep a single .env with all REMOTION_APP_* values for both example scripts.
Run example scripts from packages/lambda-python.
Validate env up front to fail fast.
Re-use the same region across function and site.

When it happens

Trigger: Running `python testclient_render_still.py` without REMOTION_APP_REGION in .env, or running from a directory where load_dotenv() does not find the file.

Common situations: Missing/blank .env in packages/lambda-python; renamed env var; CI with stripped environment.

Related errors

AI-assisted analysis of remotion-dev/remotion@78fe4bb3fd (2026-08-12). Data as JSON: /api/errors/beaf87ed872f5afe. Report an issue: GitHub.