Major Time Machine issues, won't let me update!

[MK25toLife]

I tried to do my normal update today and then it said I didn't have enough room on my external, I got real frustrated and deleted everything off the external.

So now I am trying to back everything up again. I am using 432GB's on my iMac, on my external I have 465GB of free space. However, when I go to run the Time Machine it says: "This backup is too large for the backup volume. The backup requires 510GB but only 465GB are available."

How can this be? What do I need to do to back up everything again? Your help is very much appreciated. Thank you.

 

[alphaod]

You need to first turn off Time Machine; then you can open Disk Utility to reformat the drive; afterward, you can turn of Time Machine again and restart the back up.

This will delete all your backups.

 

[MK25toLife]

You need to first turn off Time Machine; then you can open Disk Utility to reformat the drive; afterward, you can turn of Time Machine again and restart the back up.

This will delete all your backups.

I already did that, that's why there is 465GB of free space.

 

[Decrepit]

The error message seems to imply that you literally have over 500GB of data to backup, and it's too big for your drive.

You might want to make sure your main hard drive isn't corrupted and reporting much more space in use than is possible.