Time Machine

[Zejtun]

I have an external 1gig HDfor my Time Machine. It was backing up my old iMac running Yosemite. I have since bought a new iMac running Catalina. Do I have to reformat the HD to APFS from HFS or will TM still work?
Thanks,

 

[CoastalOR]

Do not change the format of the drive used for TM. Apple still only supports HFS+ format for TM drives.

 

[Zejtun]

Do not change the format of the drive used for TM. Apple still only supports HFS+ format for TM drives.

Thanks