How to Fix the AWS S3 Access Denied Error

Introduction

The AWS S3 “Access Denied” error is a common issue when working with Amazon S3.
It usually appears when an application or user tries to access a bucket or object without proper permissions.
This error can occur in development, CI/CD pipelines, or production environments.
In most cases, the problem is related to IAM policies, bucket policies, or object ownership.
This guide explains the most common causes and practical steps to fix the issue.

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Why AWS S3 returns an Access Denied error

An Access Denied error means AWS explicitly blocked the request.
Common causes include:

• Missing or incorrect IAM permissions
• Bucket policy denying access
• Object-level permissions or ownership issues
• Block Public Access settings
• Using the wrong AWS account, role, or region

Identifying which layer is denying access is the key to resolving the issue.

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How to fix the AWS S3 Access Denied error

Check the IAM policy permissions

Start by verifying the IAM user or role permissions.

 

{
  "Effect": "Allow",
  "Action": [
    "s3:ListBucket",
    "s3:GetObject",
    "s3:PutObject"
  ],
  "Resource": [
    "arn:aws:s3:::my-bucket",
    "arn:aws:s3:::my-bucket/*"
  ]
}

Make sure:

• The required S3 actions are included
• Both the bucket and object ARNs are defined
• The policy is attached to the correct user or role

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Verify the bucket policy

A bucket policy can override IAM permissions.

 

{
  "Effect": "Allow",
  "Principal": {
    "AWS": "arn:aws:iam::123456789012:role/MyRole"
  },
  "Action": "s3:GetObject",
  "Resource": "arn:aws:s3:::my-bucket/*"
}

Check for:

• Explicit Deny statements
• Incorrect principals
• Missing object-level permissions

An explicit deny will always block access, even if IAM allows it.

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Review Block Public Access settings

S3 Block Public Access settings can prevent access unexpectedly.

Steps to check:

• Open the S3 bucket in the AWS console
• Go to Permissions → Block public access
• Confirm whether public access is intentionally blocked

For private buckets, this is usually correct.
For public assets, this setting may need adjustment.

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Check object ownership and ACLs

Object ownership issues are common when files are uploaded from another AWS account.

aws s3api get-object-acl --bucket my-bucket --key file.txt

If ownership is the problem:

• Enable Bucket owner enforced ownership
• Avoid using ACLs when possible

This approach is generally recommended in newer S3 configurations.

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Confirm the AWS region and credentials

Using the wrong region or credentials can also cause Access Denied errors.

aws configure list

Verify:

• Correct AWS account
• Correct IAM role or user
• Correct region

In CI/CD environments, double-check environment variables and assumed roles.

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Common mistakes to avoid

• Assuming IAM permissions alone are enough
• Forgetting that bucket policies can override access
• Ignoring Block Public Access settings
• Mixing ACL-based and policy-based access
• Using credentials from the wrong AWS account

Most S3 access issues come down to policy mismatches.

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Final thoughts

The AWS S3 Access Denied error is usually a permission or configuration issue.
Start by checking IAM policies, then move to bucket policies and ownership settings.
Avoid quick fixes like making buckets public unless it is truly required.

Because AWS permissions can change over time, always verify the current configuration in the AWS console or official documentation.