USB 3 bootable installer won't install Catalina "The bless tool was unable to set the current boot disk."

Thank you. I can certainly try HFS+ and will report back. T2 security is a new animal and I've already allowed "External Boot" So when you say disable the security settings do you mean use "No security"? They've let a cat loose among the pigeons here. I've been on the tech support since this arrived a week ago with my backup software company (CCC) and my disk manufacturer (Glyph) - who are 2 of the very best American third party Mac companies and so far - they don't have answers.

Hi this my reply to your last 2 responses.

Reformatted to HFS+

Ran my "Install macOS Catalina" disk

Examined the external 4TB Glyph with DU and it says Catalina is installed.

Try to boot up from that and it doesn't show up.

The startup sequence is very unprofessional-looking - with flashing white, grey and dark grey screens - looking to me for all the world like a poorly or hastily programmed piece of software... leaving a lot of very angry customers like me who spent $7,000 Canadian for a better computer and now can't use their external drives...

Good luck to all of us. I'm calling Apple again.

First of all, thanks @dialbrain for your support and suggestions with this tricky situation. After speaking wth 4 Senior Apple Advisors over the past few days, I have a solution to the problem of APFS, Catalina, a total inability to make my external HFS+ RAID drives bootable on my new 16" MacBook Pro by following Apple's online instructions and the growing fear that I might now have to replace my 36 TB worth of Archive drives with SSD's.

Here is how it worked: I used 2 older MacBook Pros - a 2015 and a 2012, which I'm now about send back to Apple for their refund deal. For High Sierra my 2012 MacBook Pro had High Sierra installed, and I simply searched Google for "get macos high sierra" > Downloaded the installer > made sure the drive I wanted to install on was formatted with the Scheme: GUID Partition Map and the Format: Mac OS Extended (Journaled) > Opened the installer > chose my RAID drive > clicked install > and followed the online instructions > installation began > the Mac restarted and installation completed > then I tested the installation by restarting from the RAID drive with the new installation of High Sierra > Later when Catalina development has settled down, and when my 32-bit apps have been replaced by their developers with 64-bit, I can replace High Sierra by using the normal instructions to update my OS.

I'm not going to list all the problems I encountered when trying to update disks to APFS and installing Catalina directly (some of them are above). I can just say that this has worked. And unless there's some unknown problem, tomorrow I will have another HFS+ RAID drive - this time with Mojave installed. And with this I can boot from all my backups, keep using Carbon Copy Cloner and my beloved Glyph drives. SSD's of course are no problem updating to Catalina. It was just HFS+ and RAID drives that drove me nuts.

One final thing - the story that Macs can no longer boot from RAID drives is not true and I hope this helps someone else with the problem. I could not have done this without the Senior Advisors at Apple and the Apple Support Community.

Update: Problem unsolved. I was able to install High Sierra, Mojave and Catalina on various drives by going back to my 2015 and 2012 Macs, however the newly HFS+ re-formatted drives will not show up on the new 16" MBP with Catalina.

One of the 8TB Glyph RAID-0 drives has been formatted APFS, has Catalina on it and will show up with the Apple USB C to USB-A adapter and on my new Glyph dock. This says to me that I have one drive right and need to make the others the same.

I want to move 36TB of backup data around to organize it, delete duplicates and make sure I have 2 or 3 accessible copies of what's on my externals. And everything needs to work on the new faster computer.

Tried again to install Catalina from App Store and get the attached error

It is. It's on RAID-0.

I did speak to Glyph. I suppose I could reformat as JBOD.

OK. Thanks - on with Apple now and will report back...

Waiting for Apple. My secondary question for them is - can Catalina be installed on a RAID drive and if so, how?