Access Denied when accessing S3 bucket

AWS S3 uses a strict permission model that requires explicit permissions to access buckets and objects. The Access Denied error means your IAM user or role does not have sufficient permissions to perform the requested operation on the S3 bucket or object.

Common Causes

1. Bucket Policy Restricts Access
   The bucket policy may deny access to your user/role or IP range.

2. IAM Policy Missing Permissions
   Your IAM user or role lacks the necessary s3:GetObject, s3:ListBucket, or other permissions.

3. Object-Level ACL Issues
   The object’s Access Control List (ACL) may not grant your user or role permission.

4. Bucket Ownership and Object Ownership Mismatch
   If the bucket owner and object owner differ, the object may not be accessible unless ACLs or policies allow it.

5. Block Public Access Settings
   AWS S3 can block all public access on buckets and objects — sometimes too restrictive for your use case.

6. Cross-account Access Without Proper Permissions
   When accessing buckets owned by a different AWS account, explicit cross-account permissions are required.