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AWS S3 Access Denied: Causes and Fixes

Last reviewed: 9/14/2026
3 solutions

Exact Error Message

AccessDenied

Quick Fix

Check IAM policy permissions and bucket policy: Ensure user has s3:* permissions for the bucket.

What This Error Means

S3 AccessDenied occurs when the IAM user or role doesn't have the necessary permissions to perform the requested action on the bucket or object.

Common Symptoms
  • •Cannot access S3 bucket
  • •Upload/download operations fail
  • •AccessDenied error in logs
  • •Cannot list bucket contents
Common Causes
  • •IAM policy missing required permissions
  • •Bucket policy denying access
  • •ACL permissions incorrect
  • •KMS key permissions missing
  • •Wrong AWS credentials used
  • •VPC endpoint policy blocking access
Diagnostic Steps
  1. 1Check IAM user/role permissions
  2. 2Review bucket policy
  3. 3Check object ACLs if used
  4. 4Verify AWS credentials
  5. 5Check VPC endpoint policy if applicable

Solutions

Solution 1: Update IAM policy
  1. 1Identify missing permissions from error
  2. 2Update IAM user/role policy
  3. 3Add required S3 actions
  4. 4Wait for policy propagation
Solution 2: Fix bucket policy
  1. 1Review bucket policy for deny statements
  2. 2Update bucket policy to allow access
  3. 3Check for principal mismatches
  4. 4Test access after changes
Solution 3: Fix KMS key permissions
  1. 1Check if bucket uses default KMS key
  2. 2Add KMS key permissions to IAM user/role
  3. 3Use customer-managed key if needed
  4. 4Verify key policy allows access
Prevention Tips
  • ✓Use IAM policies instead of bucket policies when possible
  • ✓Use least privilege principle
  • ✓Regularly audit permissions
  • ✓Use S3 bucket policies for cross-account access
  • ✓Monitor S3 access logs

Version Notes: Applies to AWS S3 with all regions

Official Documentation
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