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is there a way to install Windows 7 on an Calina iMac 27" late 2015. Bootcamp does not allow it since Mojave it only allows Win10. Downgrading my Mac to an Os before Mojave is as well as using Windows 10 not an option.(cause its ass). Using a VM is also noch practical in my case. I read about using older bootcamp versions or doing it completly youreself but could not find information on how to do that.

flood
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  • A quick search on the web and I can not find any iMac Pro's made in 2015. Are you sure this is your Mac model? – David Anderson Dec 16 '19 at 00:47
  • Yes, its not a pro, littly typo, changed it. – flood Dec 16 '19 at 11:20
  • You do realize Apple did not provide the drivers for Windows 7 for your model Mac. Apple provides a download of the "Windows Support Software" which contains the drivers for Windows 10. These drivers probably would not be backward compatible with Windows 7. Have you tried Windows 10? You may be able to active Windows 10 for free is you have a Windows 7 product key. – David Anderson Dec 16 '19 at 14:38
  • No until a month ago windows 7 was installed on that imac and working without any problems. There are drivers for Windows 7, i just dont know how to get them anymore and how to install Windows 7 when i have the drivers. – flood Dec 16 '19 at 16:39
  • According to the accepted answer to the question Does Apple offer a page that lists all versions of published Boot Camp drivers?, there is only one download available from Apple for your iMac17,1. I assume this is the same download you can get by using the Boot Camp Assistant application. According to the Apple website Install Windows 7 on your Mac using Boot Camp there is no Windows 7 download for your Mac. – David Anderson Dec 16 '19 at 18:09
  • Well, i found some posts in this forum with links to older drivers for imacs ->windows 7 from third party sides, but there was never my model mantioned. Thats what im looking for, a third party side that has the old drivers for Windows 7 for my imac. Saldy apple does not show these old drivers anymore. as i said win7 was working fine on my imac until win forced an win10 update. Im just looking for s.o. in this forum who might have had the same problem in the past and still has the old drivers to install win7 on my imac. Also as i said before Win 10 is not an option. – flood Dec 18 '19 at 03:17
  • Do you know if you had Windows 7 installed to BIOS or EFI boot? – David Anderson Dec 18 '19 at 17:05
  • No, sadly i dont know. I did not own the imac when win 7 was installed, but from what ive heard it was installed via an older mac OS that created the bootable stick and then the current drivers were installed afterwards. – flood Dec 20 '19 at 03:04

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You do not have to downgrade to a earlier version of MacOS, you just need to install High Sierra in a new APFS volume in the same APFS container that Catalina is using. You can download High Sierra by accessing the link on the Apple website How to upgrade to macOS High Sierra. After High Sierra finishes downloading, you will get the following popup message. You can click on Quit to exit the installer.

To install High Sierra, you will have to copy the installation files to a flash drive. See the Apple website How to create a bootable installer for macOS for instructions. Once booted from the High Sierra flash drive, you can install High Sierra in a new APFS volume.

Note: The installation of High Sierra on my Mac consumed about 29 GB of space. If you are space limited, then you may have to temporarily move some of your personal files off of the installation drive.

After finishing installing High Sierra, you can use the Boot Camp Assistant included with High Sierra to install Windows 7.

Note: Apple documentations does state that the Windows 7 ISO should include Service Pack 1 (SP1). You can download a Windows 7 ISO with SP1 from the Microsoft website Download Windows 7 Disc Images (ISO Files).

During use of the Boot Camp Assistant, you will encounter the following window.

enter image description here

If you click on Open Website, you will be directed to the website Install Windows 7 on your Mac using Boot Camp. You should follow the directions given on the website.

After Windows 7 is installed, you can boot to Catalina and use the Disk Utility application to remove the High Sierra volume.

Some Comments about 2015 and Newer Macs

Apple and Microsoft intended for Windows 7 to BIOS boot on Macs. The instructions given in this answer should install Windows 7 to BIOS boot. However, starting in 2015, Apple starting eliminating the ability for Macs to BIOS boot. This is why the links to download on the website Install Windows 7 on your Mac using Boot Camp end in 2014. In your case, you can either try installing Windows 7 without the Boot Camp Support Software (Window Support Software) or try the Windows Support Software that can be downloaded by using the Boot Camp Assistant.

A Note about Windows 10

If you have a Windows 7 product key, then you may be able to use this product key to install and activate Windows 10 for free. When asked for the Windows 10 product key, just substitute your Windows 7 product key. The latest Windows 10 ISO can be downloaded from the Microsoft website Download Windows 10 Disc Image (ISO File).

David Anderson
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