Modern drives use SMART (Self-Monitoring, Analysis, and Reporting Technology). If the drive has flagged sector XYZ as "pending reallocation," it means the drive is uncertain about that sector’s reliability. The LLF tool may try to force a write, the drive refuses, and the tool aborts with an offset error.
If after multiple remap attempts the same offset returns, or if you hear clicking/grinding when the head reaches that offset, hdd low level format tool format error occurred at offset
"The 'format error at offset' message is rarely a false positive. Run a S.M.A.R.T. test. If pending sectors exist, the drive is unreliable. Do not trust it with important data." Modern drives use SMART (Self-Monitoring