Toshiba L50-B can´t booth windows 8.1 from USB

How did you solve that problem? I

Use a program like RUFUS to create an UEFI bootable USB flash drive. Do do this you can follow the instruction here:
http/www.eightforums.com/tutorials/15458-uefi-bootable-usb-flash-drive-create-windows.html
In bios, keep UEFI and do not switch to CSM.
Restart and boot from USB you just created with RUFUS.
When you reach the point where it ask you in which partition to install you have to delete first all previous partition you have created on your hard drive because they are in different system which is MBR and with this clean installation you will make all GPT, acceptable for UEFI.
After all partition are deleted and you have only one, you click next and install Windows (8.1 in my case).
I have a Toshiba Satellite L50-B-1K4 and it worked fine for me.

I want to change my new P50-B-119 HDD for a SSD.
I created a USB restauration key and prodeeded to disk change-over.
First start I got a "error" screen went to the UEFI and change for "not secure boot mode" and "not UEFI(legacy)"
Now I get a Toshiba logo screen ... a dark screen ...and nothing more.

I ended-up pressing the hardware reset button at the back of the PC and...I was able to boot on the USB key!
Using the USB key software I did re-install everything... and ... I am locked again!

After a few month of non sense support emails, and a Toshiba Corporate complain, I eventually get a skilled Toshiba guy!
The "trick" is very simple : set you bios in the "default" mode : UEFI and Secure Mode.
Choose USB as first boot device,
Shut down the computer, using the bios "battery power off" option and replace your HDD with another HDD or SSD.
Put your USB bootable backup key and power again.
... Just follow instruction to re-install W8.1 and it works...

At least it worked for me...

I did not try and clone the HDD to the SSD, but I reckon I can now get any data from the HDD to the SSD so it wont be a big issue.

My trouble was because I tried in first place to clone the HDD to the SSD and fiddled with the bios parameters setup to try and find a way.
Re-installing for the System backup is the way to go... but you have to set the bios back to the "normal" values too.

Last but not least, I did not kept my SSD installed as the original HDD (1To) is a "hybrid" version and it is almost as fast as the SSD for startup. I may eventually re-install the SSD when W10 will be on test to avoid testing it on my every day job disk !

thanks!