When attempting to use Time Machine and connecting and external back up disk I've used before I am getting the message - "The disk must be erased before it can be used for Time Machine backups because it has an incompatible file system."
Ive used this same BUD to back up other Mac Book Airs and there is plenty of space left. Why am I getting this message when backing up my MacBook Pro?
PLEASE HELP!? thank you so much
One additiona possibility:
MacOS 11 Big Sur and later want to use APFS for the Time Machine backup drive format. Earlier MacOS uses MacOS Extended.
This also may present a bit of a problem when you want to continue to use this same drive on other Macs running older MacOS, as they will want to see a drive that is MacOS extended.
Consider adding an additional drive for this new situation rather than "working without a net" while you change over.
One additiona possibility:
MacOS 11 Big Sur and later want to use APFS for the Time Machine backup drive format. Earlier MacOS uses MacOS Extended.
This also may present a bit of a problem when you want to continue to use this same drive on other Macs running older MacOS, as they will want to see a drive that is MacOS extended.
Consider adding an additional drive for this new situation rather than "working without a net" while you change over.
The drives file system may be damaged, you may have upgraded to an OS with different requirements, the HDD may be getting old and senile ... there are many possibilities and knowing so few details it's pretty ,much impossible to tell definitively.
Reformatting is quick and easy. Do so as required by your OS and see if the HDD works as expected. If it does you're home free. If it doesn't ,it's time to get a new external HDD.
Time Machine Back Up Error Message
