I have a phantom startup disk

[Howard Brazee]

I booted my iMac (Mojave 10.14.3) holding down the option key and discovered 3 boot choices—my main drive, Windows, and my Time Machine drive.

I have no idea why Windows is there, as I have never created a Windows boot manager. I decided to see what happened when I selected it, and it went to a gray screen that I had to power off from.

(What would have happened if I selected my Time Machine disk?)

How do I remove that Windows option?

 

[Fishrrman]

"How do I remove that Windows option?"

Why don't you try booting from it first, and tell us what happens next...

 

[Howard Brazee]

"How do I remove that Windows option?"

Why don't you try booting from it first, and tell us what happens next...

When I decided to see what happened when I selected it, it went to a gray screen that I had to power off from.

 

[Fishrrman]

"When I decided to see what happened when I selected it, it went to a gray screen that I had to power off from."

OK, now you know it's not anything "bootable".
If everything else is still running as it should, I'd just leave it alone.
Perhaps someone else will step in and explain it...

 

[treekram]

I booted my iMac (Mojave 10.14.3) holding down the option key and discovered 3 boot choices—my main drive, Windows, and my Time Machine drive.

I have no idea why Windows is there, as I have never created a Windows boot manager. I decided to see what happened when I selected it, and it went to a gray screen that I had to power off from.

(What would have happened if I selected my Time Machine disk?)

How do I remove that Windows option?

If something Windows-related, it could be a utility not just the OS, has touched the computer, it could have put that Windows boot option there. If nothing like that has touched your iMac, it might be on an external drive, if you have one connected. So make sure you have no other external drives connected and see if the Windows options disappears.

If you only have your internal disk connected and you still have the Windows boot option, I would suggest you look at the following:
https://apple.stackexchange.com/questions/122192/remove-windows-entry-from-mac-boot-loader

I have used the steps described in this link so they are correct. If the problem you're having is similar to what's pictured in the article, skip the section which starts with "which is wierd" (which uses the old Disk Utility) to the first answer (it has 17 votes the last I saw). You need to use the Terminal app (in the Applications/Utilities folder) to execute the steps. If you don't want to use the Terminal, there's an app that's suggested later on (search for "rEFInd"). I have not search for this app so I can't tell you if it's still around or if it works. Once the EFI partition is mounted, it should show up on the Finder under "efi".

The article says that "for extra safety I would recommend renaming" (the Microsoft and Boot directory) but unless you want to keep them, there's very little chance of anything bad happening by deleting these directories. Also, instead of typing in the commands to unmount (the "umount" command), you should be able to just eject the "efi" disk in the Finder and for me at least, it will typically delete the entry. You can type in the "ls /Volumes" command to make sure.

 

[Howard Brazee]

I tried this:https://www.macobserver.com/tips/quick-tip/macos-removing-windows-efi-boot-entry/

But I guess I'll live with it.

 

[treekram]

I tried this:https://www.macobserver.com/tips/quick-tip/macos-removing-windows-efi-boot-entry/

But I guess I'll live with it.

The instructions in the link are pretty much the same as the article that I linked. This should have worked. If you can live with what you got - OK - but if you do revisit this again, I would suggest re-tracing the steps mentioned in these articles.

 

[Howard Brazee]

I tried both:
Getting rid of Windows boot option
From https://www.macobserver.com/tips/quick-tip/macos-removing-windows-efi-boot-entry/

~ > diskutil list
/dev/disk0 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *121.3 GB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_APFS Container disk2 121.1 GB disk0s2

/dev/disk1 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *1.0 TB disk1
1: EFI EFI 209.7 MB disk1s1
2: Apple_APFS Container disk2 1000.0 GB disk1s2

/dev/disk2 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +1.1 TB disk2
Physical Stores disk0s2, disk1s2
1: APFS Volume Macintosh HD 818.4 GB disk2s1
2: APFS Volume Preboot 42.1 MB disk2s2
3: APFS Volume Recovery 517.0 MB disk2s3
4: APFS Volume VM 24.6 KB disk2s4

/dev/disk3 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *3.0 TB disk3
1: EFI EFI 314.6 MB disk3s1
2: Apple_HFS My Book 3 TB 3.0 TB disk3s2

/dev/disk4 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: FDisk_partition_scheme *7.8 GB disk4
1: Apple_HFS PNY 8GB 7.8 GB disk4s1

/dev/disk5 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: FDisk_partition_scheme *8.0 GB disk5
1: DOS_FAT_32 BRAZEECARD 8.0 GB disk5s1

/dev/disk6 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: FDisk_partition_scheme *61.5 GB disk6
1: Windows_FAT_32 BRAZEE 61GB 61.5 GB disk6s1

/dev/disk7 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *64.0 GB disk7
1: EFI EFI 209.7 MB disk7s1
2: Apple_HFS Green 63GB 63.7 GB disk7s2

~ > sudo mkdir /Volumes/EFI
Password:
~ > sudo mount -t msdos /dev/disk7s1 /Volumes/EFI
~ > cd /Volumes/EFI/EFI
/Volumes/EFI/EFI > ls
/Volumes/EFI/EFI > rm -rf Microsoft
/Volumes/EFI/EFI >


This didn’t work. Next, I tried this (from https://apple.stackexchange.com/questions/122192/remove-windows-entry-from-mac-boot-loader):
~ > sudo gpt -r show /dev/disk0
Password:
gpt show: unable to open device '/dev/disk0': Operation not permitted
~ > sudo mkdir /Volumes/EFI
~ > sudo mount -t msdos /dev/disk7s1 /Volumes/EFI
~ > sudo unmount /Volumes/EFI
sudo: unmount: command not found
~ > sudo rmdir /Volumes/EFI
rmdir: /Volumes/EFI: Resource busy

This didn’t work either.

 

[treekram]

What I see is 2 internal drives which appears to be a fusion drive, one external HDD and 4 flash drives of some sort. Is that correct? If the commands you have in your post are the only commands you entered, then you only would have removed the Microsoft directory from one of the flash drives.

As I mentioned earlier, it would easier to remove the external drives to see if the Windows boot is coming from one of your internal drives or one of your external drives.

I also mentioned earlier that in the link I had, you should ignore the part of the instructions between the "which is weird" and the Answers section which you didn't do. No matter. You can use the www.macobserver.com instructions with the following modifications:

~ > sudo mkdir /Volumes/EFI
Password:
~ > sudo mount -t msdos /dev/disk7s1 /Volumes/EFI

MODIFICATION:
Instead of /dev/disk7s1, you have to go through this process with: /dev/disk0s1, /dev/disk1s1
Again, it will be easier if you remove your external disks and see if the problem is in one of your internal disks.
END MODIFICATION

~ > cd /Volumes/EFI/EFI
/Volumes/EFI/EFI > ls

MODIFICATION
You need to see if the "Microsoft" directory show up in the output of the "ls" command. If it doesn't, then you don't have to do the "rm -rf Microsoft" command.
If you don't see either the "Microsoft" or "Boot" directory on your internal disks (/dev/disk0 or /dev/disk1), then the problem is with the external drives or some other unusual issue. The link I had also mentioned removing the "Boot" directory. Now because you have a fusion drive, for safety sake (I don't think Apple uses it in a fusion setup, but I have not used fusion drives so I can't be 100% sure, only 95%), you can leave this directory alone if it appears on your internal drives and see if just removing the "Microsoft" directory will stop the phantom boot. Just note if you find the "Boot" directory and on which drive (/dev/disk0 or /dev/disk1) you find it.
END MODIFICATION

/Volumes/EFI/EFI > rm -rf Microsoft
/Volumes/EFI/EFI >

MODIFICATION
Once you have done this for /dev/disk0s1, before doing it for /dev/disk1s1, you have to unmount what you mounted. It should appear in the Finder and you should be able to eject it from the Finder. But before you do that you need to enter the following command: "cd" and then press the enter key. if the "EFI" is not ejectable in the Finder (sometimes it is, sometimes it isn't, in my experience), then you can enter:
sudo umount /Volumes/EFI
After entering in this command, you can go through and do the same procedure for /dev/disk1s1.
END MODIFICATION

This is not the easiest thing to do and if you decide to live with the Windows boot showing up, to me that's a viable alternative if you don't feel comfortable doing all of this. The only command that can be really bad is the "rm -rf" command if you put the wrong directory after the "rm -rf".

 

[Howard Brazee]

I disconnected all of my disks then rebooted. I hadn't noticed multiple EFI.
~ > diskutil list
/dev/disk0 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *121.3 GB disk0
1: EFI EFI 209.7 MB disk0s1
2: Apple_APFS Container disk2 121.1 GB disk0s2

/dev/disk1 (internal, physical):
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *1.0 TB disk1
1: EFI EFI 209.7 MB disk1s1
2: Apple_APFS Container disk2 1000.0 GB disk1s2

/dev/disk2 (synthesized):
#: TYPE NAME SIZE IDENTIFIER
0: APFS Container Scheme - +1.1 TB disk2
Physical Stores disk0s2, disk1s2
1: APFS Volume Macintosh HD 817.1 GB disk2s1
2: APFS Volume Preboot 42.1 MB disk2s2
3: APFS Volume Recovery 517.0 MB disk2s3
4: APFS Volume VM 24.6 KB disk2s4

~ >

I'm going to reboot to Startup Manager and see what I get. If the Windows partition is on one of my memory cards, I will use trial and error to discover which one.

 

[Howard Brazee]

Odd. The problem is my PN disk.
/dev/disk4 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: FDisk_partition_scheme *7.8 GB disk4
1: Apple_HFS PNY 8GB 7.8 GB disk4s1

I formatted this FAT:
/dev/disk4 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: FDisk_partition_scheme *7.8 GB disk4
1: DOS_FAT_32 PNY 8GB 7.8 GB disk4s1

And it still was the problem. In fact, when I got to the boot menu, pulling that memory card out made the "Windows" option disappear. The only options were to boot to my Mac's main disk, or to the Time Machine (I don't know what would have happened had I selected that 2nd option).

Weird. While playing around, there were times when it my Mac would sit for a long time before continuing with the boot up.

 

[DeltaMac]

This would be a good opportunity to check that your System Preferences/Startup Disk prefs show that your macOS boot drive is selected. You will have to unlock that pane to make sure about that. Click on your boot drive, so it is highlighted.

 

[Howard Brazee]

This would be a good opportunity to check that your System Preferences/Startup Disk prefs show that your macOS boot drive is selected. You will have to unlock that pane to make sure about that. Click on your boot drive, so it is highlighted.

Oddly enough, when I checked that the other day—and again right now, that drive was the only option I could see there. I haven't tried using Target Disk Mode, but suspect it may be the same thing as booting while holding option down. If so, then when I do it with my wife's newer computer with a wireless keyboard, I wouldn't need to plug her keyboard in.

 

[DeltaMac]

The Startup Disk pane does not necessarily show the same options as the Option-boot picker screen.
The important check is to make sure that your macOS boot drive is actually selected. As I said earlier, you have to unlock that pane to check that.
(Target Disk Mode does not boot to a system. It is a hardware mode that allows you to access the hard drive directly from another computer, using either a Thunderbolt or Firewire connection)

 

[Fishrrman]

A possible way to get rid of it:
(and this involves some work)

1. Get an EXTERNAL drive. Format it to GUID partition format, APFS.
2. Download the latest version of CarbonCopyCloner:
http://www.bombich.com/download.html
(CCC is FREE to download and use for 30 days)
3. Clone contents of internal drive to the external drive.
4. BOOT FROM the external cloned bootable backup
5. Open Disk Utility and ERASE the internal drive (back to GUID partition map, APFS)
6. RE-CLONE the contents of the backup drive BACK TO the internal drive
7. This -might- get rid of the EFI boot partition. Not certain, but that's what I would try.

However -- as far as I'm concerned, if this "phony boot partition" just shows up in the startup manager, but DOESN'T AFFECT THE OPERATION OF THE MAC OS, I'd just let it "sit there" and... ignore it.

As a wise guy said once long ago:
"Don't sweat the small sh**!"

 

[treekram]

A possible way to get rid of it:
(and this involves some work)

1. Get an EXTERNAL drive. Format it to GUID partition format, APFS.
2. Download the latest version of CarbonCopyCloner:
http://www.bombich.com/download.html
(CCC is FREE to download and use for 30 days)
3. Clone contents of internal drive to the external drive.
4. BOOT FROM the external cloned bootable backup
5. Open Disk Utility and ERASE the internal drive (back to GUID partition map, APFS)
6. RE-CLONE the contents of the backup drive BACK TO the internal drive
7. This -might- get rid of the EFI boot partition. Not certain, but that's what I would try.

However -- as far as I'm concerned, if this "phony boot partition" just shows up in the startup manager, but DOESN'T AFFECT THE OPERATION OF THE MAC OS, I'd just let it "sit there" and... ignore it.

As a wise guy said once long ago:
"Don't sweat the small sh**!"

Ignore this. The poster hasn't read through the entire thread.

Odd. The problem is my PN disk.
/dev/disk4 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: FDisk_partition_scheme *7.8 GB disk4
1: Apple_HFS PNY 8GB 7.8 GB disk4s1

I formatted this FAT:
/dev/disk4 (external, physical):
#: TYPE NAME SIZE IDENTIFIER
0: FDisk_partition_scheme *7.8 GB disk4
1: DOS_FAT_32 PNY 8GB 7.8 GB disk4s1

And it still was the problem. In fact, when I got to the boot menu, pulling that memory card out made the "Windows" option disappear. The only options were to boot to my Mac's main disk, or to the Time Machine (I don't know what would have happened had I selected that 2nd option).

Weird. While playing around, there were times when it my Mac would sit for a long time before continuing with the boot up.

For the long wait, do what was suggested in post #12. If that doesn't solve it, report back.

I checked and on one of my flash drives, which is probably 10 years old (and has not been reformatted in it's 10-year life), will show up as a Windows boot disk. Like yours, it has a FDisk_partition_scheme with a WINDOWS_FAT_32 format (vs. DOS_FAT_32) and no EFI partition. But on another flash drive, which is recent, also not reformatted with a similar partition but does not show as a Windows boot disk. On the flash drive that shows up as bootable, I don't see any files which would typically be used for booting.

If you want to try this, since it's something easy thing to do (since it looks like you don't have any data on the flash drive) is to erase/format is to erase again using Disk Utility, this time changing the scheme from "Master Boot Record" to "GUID Partition Map".

There could be something in the partition table which the Mac sees as a bootable flash drive - I don't know. Probably if one took the time to search, one could find out. If what I suggested in changing the partition scheme doesn't work, one can completely erase the flash drive - this requires entering a command in the Terminal app. For me, I don't think it's not worth the effort - just be aware that the specific flash drive you have is seen as a bootable flash drive even though it won't boot.