Installation of Catalina done - but Catalina doesn’t start.

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Level 1

4 points

Installation of Catalina done - but Catalina doesn’t start.

My (late 2015) iMac works well with the Mojave OS. I wanted to try Catalina - but from an external SSD. First I tried via the terminal sudo /Volumes/Mojave/Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia , which worked well up to a never ending last booting process, when the display didn’t change any more after many hours, with the white bar below the apple symbol fully filled.

An ⌥ reboot showed two new APFS volumes on the SSD: a newly created Catalina (~11 GB), and one more Catalina - data volume (≈3.3 GB). As the former was indicated as bootable, I tried it, but after a few minutes this ended with the same never ending black screen scenario as above.

The very same behavior reoccurred when I started the /Volumes/Mojave/Applications/Install\ macOS\ Catalina.app/ directly to this SSD.

What’s going wrong there? Isn’t it possible to boot Catalina from an external disk with this method - even if it’s shown as bootable?

iMac 27″, macOS 10.14

Posted on Aug 17, 2020 2:47 PM

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Answer 1

hexerik Author

Level 1

4 points

Aug 19, 2020 11:12 AM in response to hexerik

hexerik wrote on Aug 17, 2020 4:07 PM in response to Barney-15E : "I'll come back with the results."

Ok. I erased my SSD and (again) set it to GUID Partition Table and APFS format as you advised. I once more tried to install Catalina - this time not via my macOS Catalina install program in the Application folder, but via the internet. Again the second boot process didn’t come to an end (I left it overnight, with the loading bar already filled to its end after about half an hour). Next day I booted my internal Mojave and checked the SSD: again there were these two volumes named SSD Catalina and SSD Catalina - Data (SSD Catalina is the disk’s name), with the same size as before:

 An alt boot again indicated the SSD Catalina as bootable - but this wasn’t so: same old story with the black apple screen and totally filled loading bar forever.

Guess I’ll stay in the Mojave desert.😉. Works well.

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Answer 2

hexerik Author

Level 1

4 points

Aug 19, 2020 1:03 PM in response to Barney-15E

Hi Barney, you're totally right: your last question 😀 solved my problem! The SSD is umblamable - its connection was the culprit! SSD Catalina then booted within less than a minute, and the installation of the personal facilities was also done in a few minutes.

Do you know the reason? There was no other active device on the HUB before - but two more connected.

Would have saved me a few hours if I had known this before! But I'm still adaptive and love to learn new interrelations.

Thank you, Barney!

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Answer 3

Barney-15E

Level 10

117,238 points

Aug 17, 2020 3:25 PM in response to hexerik

Why are you making a bootable installer for an external drive?

What did you use as the destination for the bootable installer?

Something went wrong with the installation.

Just run the installer from the internal drive (Applications folder), and pick the external as the destination for the install.

You should probably erase the external completely and format it as APFS before running the installer again.

In Disk Utility, select Show All Devices from the View button popup menu.

In the device list, select the external SSD device.

Use Erase and set it to GUID Partition Table and APFS format.

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Answer 4

hexerik Author

Level 1

4 points

Aug 17, 2020 4:07 PM in response to Barney-15E

Barney-15E wrote "Why are you making a bootable installer for an external drive?" You're right: actually this wasn't was I really wanted. I shouldn't have installed an installer.

Barney-15E wrote "Something went wrong with the installation." Sure - because I did it wrong with the first method: createinstallmedia. Actually this is not what I really wanted: create a bootable Catalina OS - not an installer for it.

Barney-15E wrote "Just run the installer from the internal drive (Applications folder), and pick the external as the destination for the install." That's what I did by my second method (s. above) - unfortunately the result was the same as before: the two APFS volumes (Catalina and Catalina - data) were deleted - not by myself, but by the Install\ macOS\ Catalina.app/ - and recreated by it. Again shown as bootable - but it wasn't so.

Now I'll follow your advice, reformat the SSD and try once more the installation: in fact the OS installation, not the installer one.

I'll come back with the results. Thank you, Barney!

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Answer 5

Barney-15E

Level 10

117,238 points

Aug 17, 2020 7:41 PM in response to hexerik

Catalina will create two volumes, Macintosh HD and Macintosh HD - Data. The first is a read-only volume for the OS, and the - Data volume is for your data and third-party software. Just mentioning in case you didn't know.

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