Error Code 0x80042405-0xa001a on MCT

Use MCT to download and create a ISO instead of directly creating the flash drive. Then manually create the flash drive as follows. Looks like a lot but it's really not, just follow the steps:

Here is a manual (non-Rufus) procedure originally posted by @NavyLCDR that I recorded and saved (with slight modifications). I've used it many times now and it works under all boot conditions, UEFI/GPT/MBR or BIOS/MBR.

1. Use the Media Creation Tool to download and save the ISO file to your hard drive.
2. Insert the USB flash drive.
3. Open a Administrator Command Prompt. It will say Administrator Command Prompt in the Title bar. Enter the following commands:
4. diskpart
5. list disk
6. select disk # <- replace # with the actual disk number of the USB flash drive
7. clean <- this will erase the disk selected above, make sure you selected the USB flash drive!
7a. If the flash drive shows as GPT then you need to convert it to MBR: convert mbr
8. create part pri
8a. sel part 1
9. format fs=fat32 quick
9a. assign
10. active
11. exit
12. exit - and if the first Command Prompt was not an Administrator Command Prompt, exit that one too.
13. Mount the ISO you downloaded. If you are using Windows 8 or 10, you only have to right click on it and click on mount. If you are using Windows 7, then you must use a program like WinCDEmu to mount the ISO file:
WinCDEmu - the easiest way to mount an ISO. And more...
14. Copy all the files and folders from the mounted ISO file to the USB flash drive.

That's as simple as it gets. Between steps 7 and 8 you can enter: "select part 1" without quotes - but it should not be necessary.
Between steps 8 and 9 you can enter: "assign" without quotes - but it should not be necessary.

I've added them in the tutorial and I do enter them as it doesn't hurt.

I was mistaken:
The clean command in diskpart automatically converts the drive to MBR. "Convert MBR" is never necessary after the "clean" command.
The clean command in diskpart automatically converts SSDs and HDDs (even when connected to USB) to MBR. If it is a USB flash drive, then "convert MBR" is required.

Also, if you want to make sure you know what drive letter the USB flash drive gets, in step 9a above you can assign it any unused drive letter in your system such as:

assign letter=S

Then you know which drive letter to copy the files and folders from the mounted ISO to.

The clean command in diskpart automatically converts the drive to MBR. "Convert MBR" is never necessary after the "clean" command.

Didn't know that, thanks.