Resolved How to fix an external hard drive partition?

[LeoI07]

I have this 12 TB external hard disk drive with the main partition being an 11 TB exFAT partition. The thing is, this partition is somehow broken, and when it gets mounted macOS will often display an error saying "macOS can't repair the disk" and that I should back up all the files on it; macOS won't let me write any data to this partition, but all the other partitions on the disk work just fine. If I can, how do I fix this without reformatting the partition?

 

[DeltaMac]

There's some likely tools to help you, but some need you to be booted to Windows - such as Easus, or maybe a free trial for Stellar data recovery (runs on your Mac)

 

[Fishrrman]

Is the data on the Mac partition backed up?

Reason I asked:
If you start fooling around with the PC partition on a PC, it could damage the Mac partition.

I don't recommend combining Mac AND PC partitions on a single drive. Can be risky...