Time machine could not back up to AirPort base

Time Machine will not back up to My Passport when that drive is directly connected to my Mac.

It won't, unless you first select the drive as a Time Machine backup in Time Machine Preferences options. Did you go through this process?

We ask because Time Machine backs up differently to a drive connected directly to a Mac compared to a network drive connected to a router. You can't "mix" the two types of backups.

If you call Apple Support, they will very strongly recommend that you remove Clean My Mac, as will the experts over in the Catalina 10.15.x support forum.

As I mentioned previously, Time Machine is a part of the Mac operating system. We handle questions and issues with the AirPort Extreme and AirPort Time Capsule in this forum, so you might want to post over in the support forum for Catalina. The link is just below:

macOS Catalina

For what it is worth, I have used a WD 500 GB drive to back up my Mac from time to time as a test, and have never had any issues with this. But, I do not run any "cleaners", "optimizers", or other applications that purport to improve the performance of a Mac.

But, I have not tried a backup with the WD drive connected to the USB port on an AirPort Extreme. Is that what you are trying to do?

There are a number of things that happen in background when Time Machine runs. Since you are not able to run a backup with an drive directly connected to your Mac would indicate something in that process if not working.

One option is to "watch" the backup in process to attempt to see where it is failing. This may provide the clue on what is happening and a potential for working towards a solution.

To do this, you would need to run the following command in the Terminal app:

• sudo fs_usage -f -R filesys backupd

Similarly, to list any errors during the backup, enter:

• sudo log stream --predicate 'subsystem=="com.apple.TimeMachine"' --info

Is your Mac running any kind of anti-virus application? Norton in particular has caused countless problems with Catalina 10.15.x in particular, but you don't indicate what operating system you are currently running on your Mac. That would be helpful, since Time Machine is a part of the Mac operating system.

The next step would be to check your Time Machine backup drive for errors by running First Aid using Disk Utility on your Mac. Post back if you are not familiar with this procedure.

So that we can have an idea on what "tried all of the suggestions" entails, would you please list them so that we don't try offering you potential solutions that haven't already worked for you.

If you have the time and can post the "solution", that would likely help other users who have "tried everything" with no luck.