Time machine doesn't allow the external hard disk to make a back up copy
How can I get Time Machine to make backup copies again?
Apple Intelligence is now available on iPhone, iPad, and Mac!
How can I get Time Machine to make backup copies again?
How to setup and use Time Machine: Back up your Mac with Time Machine - Apple Support
I suggest you start from scratch and do all steps required, don't skip any.
Other than that, you need to provide more detail for a more comprehensive answer: https://discussions.apple.com/docs/DOC-5931
How to setup and use Time Machine: Back up your Mac with Time Machine - Apple Support
I suggest you start from scratch and do all steps required, don't skip any.
Other than that, you need to provide more detail for a more comprehensive answer: https://discussions.apple.com/docs/DOC-5931
What have you done since you last got a successful backup?
What exactly happens when you try to backup? I do you know it failed? Any error message?
Time machine doesn't allow the external hard disk to make a back up copy