How to Resolve 'Access Denied' Error When Listing Buckets in Amazon S3 Using Ruby

Hello fellow data scientists and software engineers

How to Resolve ‘Access Denied’ Error When Listing Buckets in Amazon S3 Using Ruby

Hello fellow data scientists and software engineers! Today, we’re going to address a common issue that many of us have come across when interacting with Amazon S3 using Ruby - the ‘Access Denied’ error when listing buckets.

What is Amazon S3?

Amazon S3 (Simple Storage Service) is an object storage service that offers scalability, data availability, security, and performance. It allows you to store and retrieve any amount of data at any time, from anywhere on the web.

Why does the ‘Access Denied’ Error Occur?

The ‘Access Denied’ error usually occurs due to incorrect or insufficient permissions assigned to the IAM (Identity and Access Management) user or role. IAM is a web service that helps you securely control access to AWS resources.

How to Resolve the ‘Access Denied’ Error

Let’s dive into how you can resolve this issue systematically.

Step 1: Review IAM User Policies

The first step is to review the IAM user policies. Make sure your IAM user has the necessary permissions to list buckets. The following policy allows an IAM user to list all the buckets.

  "Version": "2012-10-17",
  "Statement": [
      "Sid": "ListAllMyBuckets",
      "Effect": "Allow",
      "Action": "s3:ListAllMyBuckets",
      "Resource": "*"

Step 2: Verify the AWS Region

Ensure you’re in the correct AWS region. A common mistake is to try and access resources in a region different from where they are hosted. In Ruby, you can specify the region like this:

s3 = 'us-west-2')

Step 3: Check the Bucket Policy

It might be that your IAM user has the correct permissions, but the bucket policy is denying access. To resolve this, review your bucket policies and ensure they are not explicitly denying access.

Step 4: Use the Correct Access Keys

Ensure you’re using the correct access keys. In Ruby, you can specify the access key and secret access key like this:

s3 =
  access_key_id: 'YOUR_ACCESS_KEY',
  secret_access_key: 'YOUR_SECRET_ACCESS_KEY',
  region: 'us-west-2'

Remember to replace ‘YOUR_ACCESS_KEY’ and ‘YOUR_SECRET_ACCESS_KEY’ with your actual keys.


The ‘Access Denied’ error when listing S3 buckets in Ruby is a common issue, but with a systematic approach, you can overcome it. Remember to review IAM user policies, verify your AWS region, check the bucket policy, and ensure you’re using the correct access keys. Happy coding!


  • Ruby Amazon S3
  • Access Denied
  • IAM user policies
  • AWS region
  • Bucket policy
  • Access keys

Markdown generated by GPT-4, OpenAI.

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