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Author Topic: MBP 16" OS downgrade to Mojave  (Read 799 times)

aviv1887

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MBP 16" OS downgrade to Mojave
« on: December 01, 2019, 01:26:57 am »

Has anybody with a new MBP 16" tried to downgrade from Catalina to Mojave?  It seems not possible/allowed according to Apple.  Anybody has done this succesfully and cares to share?

Thank you.
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Jeremy Roussak

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Re: MBP 16" OS downgrade to Mojave
« Reply #1 on: December 01, 2019, 03:31:46 am »

It's very unlikely to be possible to run Mojave as the primary OS on a machine which didn't exist when it was written. A viable method of running 32-bit applications (the likely motive for wanting to keep Mojave at all), however, would be to run it in a virtual machine under Parallels, VMWare or a similar utility. I intend to try in due course.

Jeremy
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BJL

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Re: MBP 16" OS downgrade to Mojave
« Reply #2 on: December 01, 2019, 11:33:45 am »

I came here to say exactly what Jeremy just said.

Aside: It might be nice to have a Q&A category with upvoting enabled.
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aviv1887

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Re: MBP 16" OS downgrade to Mojave
« Reply #3 on: December 01, 2019, 12:27:53 pm »

Thanks for sharing your experiences.  I called with Apple and they don't have a clear answer but they did say "it should be possible".  Their policy as of Oct 24th is not not let you down grade anymore.  When I did a transfer that included OS Mojave to the 16" the computer did give me the prompt that it can not accept an older version of the OS on this computer. 
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kers

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Re: MBP 16" OS downgrade to Mojave
« Reply #4 on: December 01, 2019, 05:13:00 pm »

I can imagine you like to have the 16 inch mbp AND have the ability to run 32 bit software.
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Manoli

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Re: MBP 16" OS downgrade to Mojave
« Reply #5 on: December 02, 2019, 04:00:36 am »

Has anybody with a new MBP 16" tried to downgrade from Catalina to Mojave? 
It seems not possible/allowed according to Apple. 

The first step is to remote boot your new MBP off an external HD or SSD with Mojave, or earlier OS, installed.
That will tell you if the MBP can run the older OS.

https://support.apple.com/en-us/HT202796
(also possible by holding down the <alt> key whilst booting).

If it can, second step (here comes the gotcha) you'll need an installer for the older OS, or try searching Apple support for 'Mojave installer download' and do a clean install.

edit:
judging by this thread its possible
https://discussions.apple.com/thread/250636232

IIRC, macOS 10.12 (Sierra) was the last stand alone installer. 
macOS 10.13 & 10.14, High Sierra and Mojave, are direct downloads fm Apple.
« Last Edit: December 02, 2019, 04:55:15 am by Manoli »
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Joe Towner

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Re: MBP 16" OS downgrade to Mojave
« Reply #6 on: December 02, 2019, 11:37:58 am »

IIRC, macOS 10.12 (Sierra) was the last stand alone installer. 
macOS 10.13 & 10.14, High Sierra and Mojave, are direct downloads fm Apple.

DiskMakerX does a great job making bootable install media for current and older OS'es. If you don't have the OS downloaded, it'll even pull it down for you.

A workaround to get Mojave or such on a Mac that you'll be using for a while would be to setup a VMware Fusion VM of an earlier OS like Mojave (or even earlier).  That way when 10.17 comes around, you're still running those apps.  Can also use VirtualBox or Parallels, but I'm a VMware guy from way back.
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Jeremy Roussak

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Re: MBP 16" OS downgrade to Mojave
« Reply #7 on: December 02, 2019, 03:41:35 pm »

Manoli, that thread indicates only that it is possible to revert to Mojave after having installed Catalina on a machine which could run both. It tells you nothing about whether a 16" MBP, which post-dates Mojave and comes with Catalina pre-installed, could run Mojave, an OS written at a time when the model didn't exist.

I'm not sure what you mean by "direct downloads from Apple". What you get when you download is an installer; I have a Mojave installer sitting on my disk, waiting for the day I get a 16" MBP and want to run Mojave in a VM. I downloaded it from Apple. There's a thread in talk.tidbits.com which discusses where at Apple to get installers for older OSs.

Jeremy
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digitaldog

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Re: MBP 16" OS downgrade to Mojave
« Reply #8 on: December 02, 2019, 03:51:50 pm »

AFAIK, the 16"MBP uses the same chips and the earlier 15" that can run Mojave. That doesn't mean Apple didn't do something to force Catalina. But until someone actually tries, we're all guessing.
I'd like to know the facts. I do have want bumps for the newer machine but I have software that I'd like to run 32-bit even if occasionally from another boot disk. If the new 16" can't do that, I would personally pass and go for the last version that can run Mojave. 
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Andrew Rodney
Author “Color Management for Photographers"

Manoli

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Re: MBP 16" OS downgrade to Mojave
« Reply #9 on: December 02, 2019, 08:09:17 pm »

I'm not sure what you mean by "direct downloads from Apple". What you get when you download is an installer; I have a Mojave installer sitting on my disk, waiting for the day I get a 16" MBP and want to run Mojave in a VM. I downloaded it from Apple. There's a thread in talk.tidbits.com which discusses where at Apple to get installers for older OSs.

Jeremy,

The Mojave downloader is a ‘stub’ (IIRC about 1.5gb) Apple now need you to be connected to the internet and the bulk of the OS is downloaded directly from Apple (as they do with iOS installs and upgrades). The ‘full’ installers, prior to and including 10.12 Sierra, are circa 5gb.

... It tells you nothing about whether a 16" MBP, which post-dates Mojave and comes with Catalina pre-installed, could run Mojave, an OS written at a time when the model didn't exist.

OS downgrades, now unsupported by Apple, are a stab in the dark (and also a potential question mark over how this might affect the manufacturers guarantee and future service).  My alternative suggestion to the OP is to keep it simple. Install the earlier OS on an external HD/SSD and remote boot - you'll soon find out, with the least disruption, should it fail.

Manoli
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Jeremy Roussak

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Re: MBP 16" OS downgrade to Mojave
« Reply #10 on: December 03, 2019, 05:21:05 am »

The Mojave downloader is a ‘stub’ (IIRC about 1.5gb) Apple now need you to be connected to the internet and the bulk of the OS is downloaded directly from Apple (as they do with iOS installs and upgrades). The ‘full’ installers, prior to and including 10.12 Sierra, are circa 5gb.

You may be correct about the size of the Mojave downloader. However, the installer I have sitting on my disk is 6.05GB and no Internet connection is required for its use. I anticipate no difficulty in installing it in a virtual machine in due course.

OS downgrades, now unsupported by Apple, are a stab in the dark (and also a potential question mark over how this might affect the manufacturers guarantee and future service).  My alternative suggestion to the OP is to keep it simple. Install the earlier OS on an external HD/SSD and remote boot - you'll soon find out, with the least disruption, should it fail.

Of course OS downgrades are a stab in the dark; you never know what files might have been changed by the new system which will prevent the old from working. I have seen no evidence, and can conceive of no reason, why a reversionary downgrade (such as discussed in your cited article but not relevant to the OP) in a Mac could possibly affect the manufacturer's guarantee or future service, when the downgraded OS had previously been used.

That said, trying to boot a 16" MBP from an external disk might be an option. The difficulty is that if the OS on that disk was created for an older machine, it is quite likely to fail.

Jeremy
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Manoli

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Re: MBP 16" OS downgrade to Mojave
« Reply #11 on: December 03, 2019, 11:53:06 am »

... I have seen no evidence, and can conceive of no reason, why a reversionary downgrade (such as discussed in your cited article but not relevant to the OP) in a Mac could possibly affect the manufacturer's guarantee or future service, when the downgraded OS had previously been used.

That said, trying to boot a 16" MBP from an external disk might be an option. The difficulty is that if the OS on that disk was created for an older machine, it is quite likely to fail.

Jeremy,

On 16" MBP, the only installed OS is Catalina, AFAIK. No other previous OS has, or will be, installed, again AFAIK.

Apple, I'm told do not, and will not, support previous boot OS's on the new 16" MBP. If that is indeed the case, I'd rather not find myself with a 'blown' motherboard (as I did twice on a 2012 MacMini) with an uncertified/unsupported OS. Not that any of this will affect your ability to run a previous OS in a Parallel's VM. It won't.

I don't follow your comment on creating an external HD/SSD. It's a relatively simple matter to format, partition and create a bootable disk (https://support.apple.com/en-gb/HT201372). Copy the installer for the desired Mac OS onto the SSD and Bob's your Uncle ...

Manoli


*Edit:
As an aside, perusing the Apple support site, pointed me to an interesting link
https://www.stclairsoft.com/Go64/
free downloadable utility to check which apps are 64-bit app compatible.
More detailed than the built-in SysReport under 'About This Mac'.
« Last Edit: December 03, 2019, 01:05:51 pm by Manoli »
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digitaldog

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Re: MBP 16" OS downgrade to Mojave
« Reply #12 on: December 03, 2019, 01:35:33 pm »

A viable method of running 32-bit applications (the likely motive for wanting to keep Mojave at all), however, would be to run it in a virtual machine under Parallels, VMWare or a similar utility. I intend to try in due course.

Jeremy
Well there's a great deal on Parallels and a lot of other useful software for one more day here:
https://appleinsider.com/articles/19/12/03/cyber-monday-leftovers-best-apple-watch-macbook-pro-airpods-and-ipad-deals-that-are-still-live
That product alone is $79 and the entire bundle is $36, so I'm tempted.
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Andrew Rodney
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Jeremy Roussak

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Re: MBP 16" OS downgrade to Mojave
« Reply #13 on: December 03, 2019, 02:42:43 pm »

Jeremy,

On 16" MBP, the only installed OS is Catalina, AFAIK. No other previous OS has, or will be, installed, again AFAIK.

I know. That's what I was writing about.


As an aside, perusing the Apple support site, pointed me to an interesting link
https://www.stclairsoft.com/Go64/
free downloadable utility to check which apps are 64-bit app compatible.
More detailed than the built-in SysReport under 'About This Mac'.

Jon Gotow is a good egg. Default Folder is one of my "must have" tools. It and my own Apollo shareware (long dead now) used to communicate with each other.

Jeremy
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aviv1887

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Re: MBP 16" OS downgrade to Mojave
« Reply #14 on: December 04, 2019, 01:25:56 pm »

Thank you all for brain storming this issue.  When I was on the phone with Apple care we did try to create the Mojave installer on an external hard drive with terminal and failed.  Either the installer I had from an earlier upgrade wasn't the right one (which I suspect since its 22mb).  She ended up calling an Apple store for me to visit to get a proper installer on the external HD which I still might do.  It still strange to me that there is not company consensus on this issue.  You guys do make me cautious when I hear fried motherboard stories and invalidating warranties.
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Joe Towner

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Re: MBP 16" OS downgrade to Mojave
« Reply #15 on: December 05, 2019, 12:39:55 am »

Grab DiskmakerX 8.0.3 and make a bootable USB install drive for Mojave. https://diskmakerx.com/download/
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