Time Machine couldn't back up to "OWC HD"

Make sure to uncheck "Put hard drive to sleep when possible" is not checked in the Energy Saver System Settings (Battery System Settings if it is a laptop). This option is only shown in Ventura when an external drive is actually connected to the computer.

Ken W wrote:

Time Machine couldn't back up to "OWC HD"

This has been happening on a daily basis for about three weeks now. I don't know what triggered it. I turned off my iMac and then back on and I was then able to get two or three hourly back ups. I now routinely lock the screen when not using the iMac because when I slept the screen I kept getting a message that the OWC HD had not been properly disconnected and I think I read somewhere that sleeping the computer was a bad thing. However, I now get this "back up not completed" message.

Can anyone give me advice on what might be going wrong?

These are all symptoms of a drive working in a state of failure...

I would try a different drive and compare your results.

the resolve would be to replace the drive

Talk to OWC if the drive is still under warranty...

If you value your user data

3-2-1 Backup Strategy: three copies of your data, two different methods, and one offsite.

More than one device, more than one backup methodology.

Back up your Mac with Time Machine - Apple Support