AuthenticationError
litellm.errors.AuthenticationError
Stack trace
litellm.errors.AuthenticationError: Provider API key missing. Please set your API key in the environment variable before making requests.
File "app.py", line 12, in <module>
client = LiteLLMClient()
File "litellm/client.py", line 45, in __init__
raise AuthenticationError("Provider API key missing.") Why it happens
LiteLLM requires a valid provider API key to authenticate requests. If the API key environment variable is not set or is empty, the client initialization fails and raises AuthenticationError to prevent unauthorized access.
Detection
Check for AuthenticationError exceptions during client initialization or API calls. Monitor logs for missing or empty API key environment variables before making requests.
Causes & fixes
Environment variable for the provider API key is not set
Set the required API key environment variable (e.g., LITELLM_API_KEY) before running your application.
Environment variable is set but empty or contains only whitespace
Ensure the API key environment variable contains a valid non-empty string with no extra spaces.
Using incorrect environment variable name for the provider API key
Verify and use the exact environment variable name expected by LiteLLM, typically LITELLM_API_KEY.
Code: broken vs fixed
from litellm import LiteLLMClient
client = LiteLLMClient() # Raises AuthenticationError: Provider API key missing
response = client.chat('Hello')
print(response)import os
from litellm import LiteLLMClient
os.environ['LITELLM_API_KEY'] = 'your_actual_api_key_here' # Set your API key here
client = LiteLLMClient() # Now initializes without error
response = client.chat('Hello')
print(response)Workaround
Catch AuthenticationError exceptions and prompt the user or system to set the API key environment variable before retrying the request.
Prevention
Always configure and verify the provider API key environment variable is set in your deployment environment before starting the application to avoid authentication failures.