Time machine couldn't complete backup to drive

Time machine is a main backup utility for mac users offered by Apple. But sometimes time machine unable to backup your data and shows error like Time machine backup failed etc.

Here are few DIY fixes to resolve the time machine backup failure issue:

1. Check external hard drive’s file system.

2. Check free disk space on external hard drive.

3. Check for junk files or other unwanted data as it might be causing problem.

4. Check if the Mac software is updated.

5. Try restarting your Mac.

6. Check if the mac and the backup drive connected to the same network.

By checking the above issues, you might resolve the time machine backup failure.

Hope it helps!

I've double checked the drive and I do have Read & Write privilege.

You shouldn't, because TM should have made that disk read-only. Of course that requirement conflicts with the dialog, so it doesn't make sense.

For that reason I suspect Time Machine concluded the disk suffered some degree of corruption and has prevented its alteration to protect what might be that Mac's one and only one backup.

I'd erase the backup disk and start a new set, but you really ought to get an additional backup drive first. You never want to be without a backup, not even for a short period of time, and that one may no longer be reliable. Create a new TM backup on a new drive, after which you can erase the Seagate and start a new set of backups on it. Even if a disk is operating in a state of failure, you can usually use them for a long time (years) before the failures become unbearably frequent.