getting "Internal client exception" while registering a user

hi every one.
I’m really new to backend less . I’m trying to register a user, but I get Internal client exception.
the SDK is the last version and I have permission for accessing internet.
what should I check in my Application?
I also attached my project.(it is really simple) (26.42MB)

Hi, Mohamad!

Did you try our Login/Registration samples?
You can get them here(press download below):</img>