Time Machine Backup Failed, because the disk I want to backup is too full

Time Machine requires a huge amount of overhead space for any backup, so when the disk is close to full, you will start to see messages like this.

You can spend a lot of time trying to get the pending backup done by manually excluding files that were going to be backed up, but chances are you will have the same issue again very soon. I have argued with Time Machine in the past about things like this, and have learned the hard lesson that it is wise to let Time Machine have her way

Best to either erase the backup disk and start over, or keep the old backups and connect a new hard drive and start Time Machine up again

Try the steps in:

If you can't back up or restore your Mac using Time Machine - Apple Support

or:

If the Time Machine backup disk for your Mac is full - Apple Support

If no other solutions work, start over: Erase your backup disk, then use Time Machine to select it as your backup disk again.

WD 1Tb external. Was previously used for TM but since erased and reformatted;

Time machine says its full when I try to use it;

Erased and reformatted/repartitioned several times with different formats to test.

Always the same.

Suggestions please?

Thanks. Mike.

Suggestions please?

Thanks. Mike.

The suggestions are provided in the thread. It has nothing to do with the backup drive. Macbook Pro2 is too full to make a snapshot.

Speaking of local snapshots launch Disk Utility and check the number of local snapshots on your boot drive. You can delete them as I did in this screenshot;

I always leave the latest snapshot. I check the number about once a month and remove all but the latest.

If you can't find a solution to the current issue you may have to erase the drive and start over from scratch.

First, 6 GB is not much space on the backup (destination target) drive. Many of my backups would fail with that little space available on the target (destination) drive.

Second, if it is your source drive, the drive being backed up, that is too full, yes the source drive requires space to store "snapshots" which are utilized for the backup. So if your source drive is getting full (you should try to keep 20% free on the source drive, at least 10% at a minimum), the backup might be unable to run.

If your internal drive does not have enough room for snapshots it may give this message.