Issues installing to external hard drive

[Bluice25]

Hello, so I am trying to create a external hard drive to boot from, so I am trying to install the gui version to it. I have the external and a usb with the iso of kali on it. I get all the way to where it says installing but then it reboots at different parts. Sometimes during the installation or one time it rebooted during finishing installation, but I can not get it to finish all the way for somereason, not sure why it keeps rebooting. But was curious if anyone else has had this issue trying to do what I am doing.

Thanks in advance!