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I installed Windows 10 64 system on my MacBook Pro 16 / 13 Retina I used to switch simply by clicking on boot camp and clicking on the partition I want to use.

But since today I can’t see the Windows partition anymore

I looked only and I tried to restart my Laptop and press and hold the Option key but when I do that, after my PC starts I reach a black screen with a locked sign as you see in the picture I uploaded.

I have to hold the power again to lose this screen and it restarts to my Windows again

Any help to how I can access my Mac iso again I have a lot of important files there

  • 2
    Could you clarify the problem? At first it sounds like you can't see the windows partition but then you write that it loads windows after you hold the power button. What can you get to load?
    – Scottmeup
    Apr 22, 2018 at 15:48
  • 1
    You keep referring to an "ISO partition." An ISO is a CD/DVD image. Are you referring to your macOS partition? If that's the case, what you're seeing appears to be FileVault encryption password. Enter your password and you should be able to boot.
    – Allan
    Apr 22, 2018 at 15:58
  • 1
    Sorry for the confusion I don’t see the MacOS partistion in my boot camp I can only load windows and I can’t switch back to Mac When I try the option hold down botton u see the pic I posted earlier
    – T-jay
    Apr 22, 2018 at 17:04

2 Answers 2


Your computer has a firmware password set and you won’t be able to boot into any other OS unless you know/remember the password. If you do not remember setting that password, you have a few options:

1) If you bought your computer directly from Apple, they can remove the firmware lock for you.

In this case, you can go to the nearest Apple Store or Apple Authorized Support center and they can remove the firmware key. Before you do that, it’s a good idea to backup your data from both macOS and Windows partitions. You can use TransMac to access macOS partitions from Windows. You will also need to provide proof of ownership of the Mac which has a locked firmware password in order for them to unlock the computer.

2) If you bought it online from someone else (i.e from Amazon)

You will have to contact the seller and ask him/her the firmware password. He/She can tell it to you and you can then remove the firmware password from Recovery Mode.

Way to boot into macOS without firmware password (Requires macOS Sierra or earlier)

Go into Bootcamp Helper control panel and there should be an option to select between OS X and Windows. Select OS X and press Reboot (or save and restart).

Source: http://osxdaily.com/2015/01/28/forgot-mac-firmware-password-what-now/


Your description is rather confused, but the the image you posted looks like a firmware password prompt (see Apple's support document #HT204455). If there's a firmware password set on your Mac, you'll need to enter it in order to invoke any alternate startup mode -- basically, anytime you hold keys down at startup to make the Mac do something other than the default startup.

Do you know the firmware password? If so, just enter it and proceed normally. If not, you have a problem, because it's (intentionally) hard to remove or change if you don't know it.

You may also be able to switch between macOS and Windows using the Startup Disk preferences (in macOS) and Boot Camp control panel (in Windows). However, as @ÖmerRıfatKuldaşlı pointed out in a comment (and this Apple support document agrees), the Boot Camp control panel doesn't support switching to APFS volumes (which High Sierra uses on SSDs). So if you have an SSD MacBook Pro and High Sierra, you'll need the firmware password to switch from Windows to macOS.

  • 1
    I don’t think Bootcamp Helper supports APFS. The control panel might not be helpful if he is on macOS High Sierra or higher.
    – user255044
    Apr 22, 2018 at 19:08
  • @ÖmerRıfatKuldaşlı Yep, looks like you're right. I'll edit my answer. Apr 23, 2018 at 1:11

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