Backblaze B2 S3 Compatible API Connection Problems

Troubleshoot software using the S3-compatible API.

Troubleshooting guide · Steps can differ by product, plan and operating system

Understand the issue

Troubleshoot software using the S3-compatible API. Before making changes, identify the account, affected device or bucket, and the precise symptom. This helps avoid changing settings that are unrelated to the issue.

What to check first

Identify the configured endpoint, region, key ID, application key, bucket, and the failing API operation.

Determine whether the issue affects one file, one device, a specific network, or the entire account. Write down any exact warning text, the approximate time it started, and the most recent change to your computer or storage configuration.

Step-by-step troubleshooting

1. Identify the product involved: B2 Cloud Storage. Computer Backup and B2 Cloud Storage have different settings, billing models and restore workflows.
2. Identify the configured endpoint, region, key ID, application key, bucket, and the failing API operation.
3. Use the B2 S3-compatible endpoint and credentials intended for that integration, verify signing and client compatibility, and review tool logs for a precise error.
4. After each change, repeat a small, safe test rather than making several unrelated changes at once.
5. Complete a small authorized list or upload request.

If the problem continues

Compare the behavior on a second trusted network or device if appropriate. Review account status, software compatibility, available storage, permissions, and any specific error response. A missing restore file, a blocked upload, and a billing restriction can look similar but require different solutions.

For backups, check the application’s latest activity and selected data. For restores, check the backup snapshot and the restore package status. For B2 integrations, capture the relevant HTTP error code and review the key scope, bucket configuration and endpoint without publishing secrets.

How to confirm the solution

Complete a small authorized list or upload request. Use a noncritical test file when possible. For a restore, inspect the contents of the recovered file, not just its name. For B2 storage, verify the object is present and accessible only to the intended users.

Prevent the issue from returning

• Keep the operating system, backup software, and supported integrations current.
• Periodically test restoring a small file rather than relying solely on a successful-backup indicator.
• Review backup exclusions, external-drive connectivity, account billing, and storage retention settings.
• Protect credentials and use the least privileges needed for cloud-storage integrations.

Frequently asked questions

Will these steps work for both Backblaze products?

Not necessarily. Computer Backup is designed for supported computer backup workflows, while B2 is object storage accessed through buckets, APIs, or integrations. Follow the instructions for your actual product.

Should I uninstall the app or delete my bucket to fix the issue?

No. First check configuration, access, and recoverability. Removing software or deleting storage before verifying your data can make recovery harder or impossible.

What information is useful when asking for help?

Provide the product, operating system or integration, exact error message, approximate time, and the troubleshooting steps already attempted. Never share encryption keys, passwords, or access tokens.

Related Backblaze guides

• How to Create a Backblaze B2 Bucket
• How to Upload Files to Backblaze B2
• Backblaze B2 Access Denied or Unauthorized
• How to Create and Manage B2 Application Keys
• Backblaze B2 Upload Failed or Timed Out