USB flash drive --assign drive letter back to dynamic from static

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  1. Posts : 24,506
    10 Home x64 (21H2) (10 Pro on 2nd pc)
       #21

    sportsfan148 said:
    How would I resolve it with my flash drive if that's the case?
    Use DISKPART, be very careful to select the right USB drive, then use its CLEAN command. That removes all partition information (you did double-check you had the USB selected? :)).

    I'm not saying gpt was the cause for you, just that it's one possible cause that's been seen before.
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  2. Posts : 27,434
    Windows 10 Pro x64 Version 21H1
       #22

    Would you also have to add the command convert mbr after the clean command?
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  3. Posts : 985
    Windows 10 Home 21H1
    Thread Starter
       #23

    Bree said:
    Use DISKPART, be very careful to select the right USB drive, then use its CLEAN command. That removes all partition information (you did double-check you had the USB selected? :)).

    I'm not saying gpt was the cause for you, just that it's one possible cause that's been seen before.
    Yes Id done everything correctly. Its a method Ive followed several times before without issue. I might be better off just using Rufus. I'm not familiar with Diskpart at all
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  4. Posts : 24,506
    10 Home x64 (21H2) (10 Pro on 2nd pc)
       #24

    Caledon Ken said:
    Would you also have to add the command convert mbr after the clean command?
    No. There's no partition info at all after CLEAN - nothing there to convert. You could use CREATE PARTITION PRIMARY after CLEAN, that makes a MPR partition. Then format it with DISKPART, Disk Management or whatever you like.
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  5. Posts : 24,506
    10 Home x64 (21H2) (10 Pro on 2nd pc)
       #25

    sportsfan148 said:
    I might be better off just using Rufus. I'm not familiar with Diskpart at all
    I've looked at Rufus and come to the conclusion it has too many options - it's all too easy to leave some obscure option selected that makes a USB that won't boot. There are so many threads complaining of that.

    An alternative to using the MCT to make a bootable USB is to use it to make an ISO file. You can then just double-click on the ISO to mount it then copy the files to a USB, prepared using DISKPART. Here's how....

    Create Bootable USB Flash Drive to Install Windows 10 (post #270)
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  6. Posts : 985
    Windows 10 Home 21H1
    Thread Starter
       #26

    I wonder if it was the GPT partitioning problem you mentioned that caused my errors. All I did was format the drive in Windows to remove the previous Windows 10 Anniversary update which was on the drive and had been successfully created with the Media Creation Tool. When youre creating your bootable drives do you format the drive manually as an extra step before you use the Media Creation Tool. I know Media creation Tool formats the drive during the Media Creation process anyway but Ive always quick formatted it in Windows to blank the USB before starting the process
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  7. Posts : 24,506
    10 Home x64 (21H2) (10 Pro on 2nd pc)
       #27

    sportsfan148 said:
    When youre creating your bootable drives do you format the drive manually as an extra step before you use the Media Creation Tool...
    No. The MCT should format for Fat32 and mark the partition as active. I'm guessing though that it's only designed to expect an mbr layout and fails at that point if it finds gpt. None of my USBs have ever been gpt, so I've not tested that (yet).
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  8. Posts : 985
    Windows 10 Home 21H1
    Thread Starter
       #28

    [QUOTE=Bree;1239221]No. The MCT should format for Fat32 and mark the partition as active. I'm guessing though that it's only designed to expect an mbr layout and fails at that point if it finds gpt. None of my USBs have ever been gpt, so I've not tested that (yet).[/Q

    I know Rufus uses GPT and recommends it for UEFI
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  9. Posts : 985
    Windows 10 Home 21H1
    Thread Starter
       #29

    Ive just checked the USB flash drive that gave me problems with the Media Creation Tool. Ive just checked it with the Diskpart instruction and the flash drive is GPT. Do flash drives normally have MBR then? I'm guessing that it may have been the USB flash drive that I once used with Rufus. That would have set up GPT on it. Can you give me a step by step if I need to convert back to MBR...if that's what required. If I can sort the problem out I'll go back to using the Media Creation Tool to create the bootable USB media. Ive searched the net and it says it can be done in Disk management. Ive just checked by right clicking on the unallocated space on the drive. Theres no convert to MBR option on the context menu. There is a tutorial on here that shows how to convert gpt to mbr disk in Windows 10 by Brink. It mentions the clean option that you mentioned with diskpart but it also says to finish with convert mbr command. It doesn't mention anything about creating a primary partition like was mentioned earlier in posts above. Is the tutorial ive just mentioned for removable drives intended for USB flash drives or is that tutorial for something different? Could you link me to the correct tutorial for the procedure if there is one
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  10. Posts : 24,506
    10 Home x64 (21H2) (10 Pro on 2nd pc)
       #30

    sportsfan148 said:
    I know Rufus uses GPT and recommends it for UEFI
    That's as maybe, but I have now confirmed that the Media Creation Tool fails with error code 0x80004005 - 0xA001A if the USB you ask it to use has a gpt partition.

    USB flash drive --assign drive letter back to dynamic from static-mct-fail-0x80004005.png

    After failure, the USB is left 'unalocated'. You can create a new simple volume using Disk Management to make it accessible again but, critically, its is STILL using a gpt partition layout. Only DISKPART or a tool like MiniTool Partition Wizard can make it MBR again.

    The MCT only fails after it has downloaded all the files it needs, verified them and created the media in preparation for copying it to the USB. It is not until this point that it attempts (and fails) to format the USB.

    Unfortunately, the MCT cleans up after itself at close, so you have to do the whole download over again next time you run it.
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