v.25.3Improvement

Use correct fallback when multipart copy

Use correct fallback when multipart copy to S3 fails during backup with Access Denied. Multi part copy can generate Access Denied error when backup is done between buckets that have different credentials. #76515 (Antonio Andelic).
Fix fallback mechanism for multipart copy to S3 during backup to handle Access Denied errors between buckets with different credentials.

Why it matters

When performing backups between S3 buckets that use different credentials, multipart copy operations can generate Access Denied errors. This feature ensures that a correct fallback method is used in such cases to avoid backup failures and improve reliability.

How to use it

This fix is applied automatically in the backup process when using S3 as a storage backend. Users do not need to enable anything manually; the system will correctly handle Access Denied errors during multipart copy and fallback accordingly.