Hello,
Thanks for using Microsoft products and posting in the community.
From my experience this problem can be caused by serval reasons. I will provide you with the solution and hope it is useful.
Make sure your USB flash drive has no corrupt files or partitions. You can try using a different USB flash drive or format your USB flash drive and use Windows 10 Download Tool to create installation media.
You may also encounter this problem if your hard drive has errors in its partition table or file system. I found a thread that mentioned how to clear the format of a hard drive by using command prompt, I hope you can try it.
Thanks for your patience and wish you everything as well!
Best Regards,
Lenka-MSFT| Microsoft Community Support Specialist