Resolving the “Unexpected Keyword Argument ‘instances'” Issue in Vertex AI

What will you learn?

In this tutorial, you will learn how to resolve the common issue of encountering an “Unexpected keyword argument ‘instances'” error when working with Google’s Vertex AI. By understanding the root cause of this error and following the steps outlined here, you will be able to effectively address and prevent such errors in your machine learning model deployments on Vertex AI.

Introduction to Problem and Solution

When integrating machine learning models with Google Cloud services, it is not uncommon to face challenges such as the “Unexpected keyword argument ‘instances'” error in Vertex AI. This error occurs due to discrepancies in parameter naming conventions required by Vertex AI for prediction requests.

Short Intro

This guide aims to provide a comprehensive solution to the unexpected keyword argument ‘instances’ error in Vertex AI. By following a structured approach and realigning our prediction request format with Vertex AI’s expectations, you will not only fix the error but also gain insights into best practices for interacting with cloud-based machine learning services.

Understanding and Solving the Problem

The key to resolving this issue lies in correctly formatting your prediction requests according to the specifications of Google Cloud’s Vertex AI. By ensuring that your data is packaged and sent in the expected manner, you can avoid errors like “unexpected keyword argument” during model inference.

To address this problem effectively, we will: – Establish communication with Vertex AI service. – Structure data payload as per expected format. – Make prediction requests using appropriate method calls.


from import aiplatform

def predict_sample(project: str,
                   endpoint_id: str,
                   location: str = 'us-central1',
                   api_endpoint: str = '',
    client_options = {"api_endpoint": api_endpoint}
    client = aiplatform.gapic.PredictionServiceClient(client_options=client_options)

    # Construct request payload according to VertexAI specifications.
    instance_list = [{"instance_key": instance} for instance in instances]
    payload = {"instances": instance_list}

    # Make prediction request
    response = client.predict(endpoint=endpoint_name,

    return response.predictions

# Copyright PHD


To ensure smooth interaction with Google’s Vertex AI platform, follow these steps: 1. Create API Client: Establish connection using PredictionServiceClient. 2. Format Request Payload: Structure your data as {“instances”: [your_data_here]}. 3. Send Prediction Request: Use .predict() method while matching parameters with deployment details.

By adhering to these guidelines, you can avoid errors related to incorrect data formatting or parameter passing.

  1. How do I install Google Cloud SDK for Python?

  2. You can install it using pip:

  3. pip install google-cloud-aiplatform
  4. # Copyright PHD
  5. What is endpoint_id?

  6. It serves as a unique identifier for your deployed model endpoint on Vertex AI.

  7. Why specify location?

  8. Specifying location helps route requests efficiently within regional services of Google Cloud.

  9. Can I send batch predictions using this method?

  10. Yes, modify payload structure based on batch prediction guidelines from Google Cloud documentation.

  11. What does �instance_key� represent in instances list?

  12. It is an arbitrary key used for defining feature names; replace it with actual features expected by your model.


Resolving issues like unexpected keyword arguments requires attention to detail when structuring data payloads for cloud-based machine learning services like Google’s Vertex AI. By following best practices and understanding service requirements, you can streamline your development process and enhance scalability of ML models deployed on cloud platforms like Vertex AI.

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