Unable to mount external drives

Looks like I have resolved the issue, finally.

I believe it was one of the 32 bit applications causing the problem and simply removing it through conventional way wasn't enough. Although I had removed those apps but still I found their entries under Applications.

To be precise:

Apple icon --> About this MAC --> System Report ---> highlight Applications from the left pan and then click on each app on the right side to see whether it's 32 bit or not.

The app you have doubt about and you have removed it but still see it here; copy the Location of it and remove it from the terminal window.

I think OS developers should update the code to take care of incompatible applications while updating the OS.

For example:

$ sudo rm -rf /Users/TheParrot/VirtualBox*/myspark

Reboot the system and that should work.

Please note that following this procedure is entiely your responsibility. If you are not well versed with Linux or command line then better get someone's help. I don't want you to remove something important.

One way around could be be backing up the file before removing it.

$ mkdir /Users/TheParrot/MyBackup

$ sudo tar -cvf /Users/TheParrot/MyBackup/myspark.tar /Users/TheParrot/VirtualBox/myspark

And to restore this file;

$ sudo tar -xvf /Users/TheParrot/MyBackup/myspark.tar

Thanks but That didn't help.

One thing that I had tried and forgot to mention that I disabled Firewall and rebooted the Mac in Normal mode. After reboot, the external USB did show up but then disappeared after 15-20 seconds.

I rebooted again, same thing and during those 15-20 seconds, I was able to mount the dmg files as well but something kicks in that kills those mount processes.

I've removed almost all the applications from my Mac thinking that may be one of these causing the issue. No luck - can't even create a bootable usb to erase and reload. Re-installed Catalina from the recovery disk - still no luck.

Spent whole day searching google and trying all kind of different things. One thing I found that many people are having issues after upgrading to Catalina. I wonder if Apple even test their OS before releasing it - afterall it's not an open source - LOL.