My external hard drive won't work with my mac anymore

In no particular order...

Are you physically swapping that disk around with Windows systems? It seems not, but you have Paragon around.

If not, you can back up the contents, use Disk Utility.app to reformat the volume using an Apple format such as APFS or HFS+, and dispense with the need for Windows NTFS format (here).

If the volume had previously been an Apple format such as APFS or HFS+ (such as happens with Time Machine), and has unexpectedly switched to Windows NTFS, then whatever was in that volume has been lost. If you’re not swapping that disk with Windows, erase it and use the Apple APFS or HFS+ formats, and dispense with Paragon and NTFS.

If you are using NTFS and are swapping that disk with Windows and are now having issues, then upgrade Paragon.

There is no way to swap between NTFS and APFS, or between NTFS and HFS+ that does not involve erasing.

If your Mac backups have been using Time Machine with this external hard disk, Time Machine uses Apple HFS+, and a switch to NTFS will have erased the backups. Time Machine uses Apple HFS+, and does not involve Paragon nor NTFS.

It’s also quite possible that an old hard disk has simply failed, though that doesn’t also convert to NTFS. That’ll usually show as corrupt or inaccessible or failed.

How the format change happened? Unclear. Usually a user requested the volume be reformatted. Or the volume here is not actually NTFS, but failed hardware or somehow corrupt.

Lune_étoilée wrote:

Thank you.

By updating this Paragon software, will I lose all my data ?

Should I try to back them up somewhere first ?

No. Updating software does not lead to data loss.

None the less always advise to have robust backup plan if you value your data—

3-2-1 Backup Strategy: three copies of your data, two different methods, and one offsite.

Boot clone https://discussions.apple.com/docs/DOC-10081

How to use Time Machine to back up or restore your Mac: https://support.apple.com/en-us/HT201250

Use DiskUtility Restore feature  https://support.apple.com/guide/disk-utility/restore-a-disk-dskutl14062/mac

         note: >System Preferences>Security & Privacy >Privacy>Full Disk Access

                  unlock the  padlock,  press the + button and add Disk Utility 

Lune_étoilée wrote:

Hello,

I have been using the same external hard drive for years to back up my macbook pro and for some reason I can't anymore. I have checked the information on my HDD and it seems that its format has changed. It is now in NTFS. I don't understand how it was changed without my knowledge but I would like to know how to change it back (and well it would be interesting to understand what has happened so that it doesn't happen again). Can we change the format without having to reset the HDD entirely ? Because I don't have enough space on my mac to transfer all the information I have on my HDD.

Thank you very much for your help !

Update the supporting software for NTFS

Tuxera

Paragon

If your Time Machine backup storage drive is the drive that now uses NTFS, then your Time Machine backups have been erased.

I prefer to run two parallel Time Machine backups. This as computers fail, and so too can and do backup storage devices, and backups can become corrupt.

For critical data, that's copied off-site.

Lune_étoilée wrote:

What does "offsite" mean in this sense (of making a copy of my data offsite) ?

If all your backups remain in your house— and your house burns down —you lose your computer and all your backups.

However—If you move one off your backups "off site" —

ex. in the boot of your car or your office location or locker at the gym or storage unit, or friends house

then you are saved by this off site backup when you need it most.

Update & Upgrade center - Paragon Software