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I can install Windows 10, but not MacOS on my iMac (Paragon disk manager). HELP!

I have a clients iMac 2012 that I upgraded to an SSD. He had bootcamp and I wanted to restore its partition to the SSD, but needed to resize it to fit. I used Paragon disk Manager and it has crippled the iMac at this point :-(.

It is now in such an unusual state and I wonder if someone here might offer some insight? It seems to get stuck and crawl super slowly on any attempts to boot any MacOS disk, including Installers for El Cap and Catalina? It seems completely unable to boot MacOS effectively. Right now I am trying to do an install via internet recovery (mountain lion) and although it seems hopeful at first, it is looking bleak now as well.

Strangely I was able to complete a Windows 10 install on it in like 15 minutes? I suspect the Paragon software did something to the BIOS or EFI on the machine itself which is causing this. It was initially running Catalina, when I foolishly involved the Pargon software :-(... Please Help!

iMac Line (2012 and Later)

Posted on Mar 17, 2020 6:13 AM

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HWTech

Level 9

69,698 points

Posted on Mar 17, 2020 7:24 PM

You should never use any third party utility (or a utility from another OS even) to manage a volume since they may not adhere to the native OS standards. For example use macOS utilities to manage macOS partitions. Use Windows utilities to create and manage Windows file systems and partitions. Same goes for Linux.

While I don't use Bootcamp, I believe you should not resize the partitions or Windows will become unbootable since the Window's bootloader will no longer be able to find the Windows system files.

Boot into Recovery Mode and use Disk Utility to completely erase the whole physical drive. You may need to click on "View" within Disk Utility and select "Show All Devices" before the physical drive appears in the left pane of Disk Utility. After you have properly erased the SSD you should reinstall macOS. Then run Bootcamp Assistant to resize the partitions for Windows and to create an Apple compatible Windows installer.

If the original drive is in working order, then you can use Carbon Copy Cloner to clone the macOS partition to a freshly erased SSD. Then you can use Bootcamp Assistant to resize the partitions and install Windows.

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44 replies

Loner T

Level 9

59,536 points

Apr 3, 2020 6:30 PM in response to Areyou486

The 2012-2014 iMacs have non-standard display connections to support DisplayPort and TB connections. Does the 'bad' display work in a fully-functional iMac, which works correctly before the 'bad' screen is attached?

Areyou486 Author

Level 1

8 points

Apr 3, 2020 7:30 PM in response to HWTech

The funny thing is that it did (If I had the patience to let it) seem to complete installs, etc. It just took 100X longer than expected to do so, with many extended periods of no apparent activity?...

I will keep updating to see if I can bring the screen back to proper operability. The dang replacement screens for these costs more than entire working used units with cracks on the glass!

Loner T

Level 9

59,536 points

Apr 4, 2020 7:04 AM in response to Areyou486

iMacs that support Target Display Mode (Use your iMac as a display - Apple Support) are very different from the ones that do not. Your iMac (21.5-inch, Late 2012) - Technical Specifications should support it, which is where the hardware differences originate from.

I prefer MacMini over an iMac, but that has it's own quirks.

Areyou486 Author

Level 1

8 points

Apr 4, 2020 9:04 AM in response to Loner T

I could see how that super cool feature may have functions that relate to the behavior I've experienced... I have a few newer laptops with faulty displays I was thinking would be cool to an iPad using that function, but you need a much newer iPad than anything I have on hand!

Areyou486 Author

Level 1

8 points

Mar 18, 2020 6:49 AM in response to Joseph_S.

I have done that and started a conversation with them... Thanks!

Areyou486 Author

Level 1

8 points

Mar 20, 2020 5:02 PM in response to Loner T

Hey Loner T,

It is a 21.5" no blade SSD slot on it. It had a 1T 2.5" HD that I replaced with the 2.5 SSD. The system ran FLAWLESSLY up until I installed the Paragon software...

Areyou486 Author

Level 1

8 points

Mar 21, 2020 6:31 AM in response to Loner T

I restored the OS to the SSD from the 1T drive originally, then reformatted a few times in my various attempts...

Areyou486 Author

Level 1

8 points

Mar 29, 2020 9:45 AM in response to Areyou486

PS: On installing the new MLB I noted that it did indeed have the blade slot. All specs I read said it did not... "Could this be the solution?" I do have one on hand...

Loner T

Level 9

59,536 points

Apr 4, 2020 11:16 AM in response to Areyou486

Take a look at Use your iPad as a second display for your Mac with Sidecar - Apple Support.

Areyou486 Author

Level 1

8 points

Mar 18, 2020 6:48 AM in response to Areyou486

Hey HWTech!

Thank you for your response! Believe me I will NEVER use third party disk utilities ever again. I have completely wiped the drive numerous times, and suspected that was the problem. Now I am pretty sure the Paragon software altered the EFI boot loader, as it asked for all kinds of permission when installing. When I attempt to install MacOS, 10.8 was the only available version I had that completed a full install a ran "reasonably" well (stuttering mouse movements, slower than a 2.7 i5 with SSD and 16 Gig RAM should). All others crawled along and never finished (even if left overnight). The windows 10 install completed in like 10 minutes and ran like an absolute dream.

I dowloaded Mac2015002EFIUpdate and had hopes that might repair whatever was done, but it will only install on 10.9.5, which is no longer available anywhere. An installer I had turned out to be NOT bootable :-(... I even tried to find information on installing it via terminal, but what I found was just a bit over my head...

I am so frustrated that I ordered a new motherboard yesterday, as I am starting to feel I may not get a software resolution... Replacing the motherboard is not something I look forward to, so any help whatsoever would be very much appreciated... PS: This utility also wiped out my main HD on my personal machine and I am in the process of trying to recover the partitions now yet...

https://discussions.apple.com/thread/251182814?answerId=252273504022#252273504022

Areyou486 Author

Level 1

8 points

Mar 21, 2020 1:09 PM in response to Loner T

Yeah, at this point the client does not care for anything from the original OS/drive and neither do I. All I care about is getting Catalina reinstalled and the machine running like a 2.7Ghz i5 with a fast SSD and 16Gig of RAM should. Even with the clean recovery installed on the brand new drive, it took way longer than it should have and you can feel it's not responsive, with pauses before accepting input and general cursor stutter, etc...

Do you think doing target mode will help me determine/fix why it's performing this way? Right now it's booting and "usable" under Mountain Lion. My thought is to try upgrading from 10.8 to 10.9 > 10.15, in hopes it kicks something loose, as of right now, removing the old drive and putting a new drive has not ameliorated the problem at all...

Areyou486 Author

Level 1

8 points

Apr 3, 2020 7:26 PM in response to Loner T

Yep, it borked the new iMac when I attached it and made it display the EXACT same behavior as the original iMac. Attaching the new screen to the original iMac made it behave exactly as it should have fast and responsive... There is definitely something amiss that the MacOS sensed. I'm thinking perhaps some type of ground? I just keep going back to how windows happily ignored whatever it is, while MacOS turned to a stuttering imbecile? Love to know the whys, but for now just happy to know the where...

PS: I was using a DP adapter to troubleshoot the iMac from an external display, without the internal display. Like I said without the internal display attached at all, the machine showcased the same stuttering nonsense. I wonder, do other iMacs act badly without the internal display attached? I know older ones did not...

Loner T

Level 9

59,536 points

Mar 19, 2020 8:52 PM in response to Areyou486

My recommendation is to wipe the newly-installed SSD.

Does your iMac have a Blade SSD? If yes, is this the SSD that was replaced? If yes, did you use an Apple SSD or a third-party SSD?

Loner T

Level 9

59,536 points

Mar 29, 2020 9:48 AM in response to Areyou486

Disconnect all SATA disks, and install just the blade SSD, and try the Diagnostics (D). You seem to have a later generation MLB.

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I can install Windows 10, but not MacOS on my iMac (Paragon disk manager). HELP!