Windows® 7 was released in 2009.
At that time, hard sectors (where files are stored) were 512 bytes in size.
Initially, hard drive sizes were manufactures in gigabyte (GB) sizes. Shortly thereafter, larger drives were developed with storage capacity for a terabyte (1,024 GB) or more. To make these drives faster and more effect, the sector size was changed from 512 to 4K (4,096 bytes). Unfortunately, the backup software in Windows® 7 does not support this new sector size. Consequently, errors will occur. Backups using newer versions of Windows®, however, will work fine.
If you have Windows® 7, you must use a drive that is formatted with 512 byte sectors. They are not easy to find. As an alternative, third-party backup software that will work with 4K sectors would be required.