Build error "File, line 926, in _bootstrap_inner" in mbed studio

Using the following URL as a reference, I created a GR-MANGO project in mbed studio and then created a custom target.

After that, when I build it in Mbed studio, the following error occurs:

I don’t know the cause, please advise me.

Hmm, it looks like something in the build process is choking on a non-ASCII character. Unfortunately it doesn’t show what file… I’d say scrub all the files you added for any non-ASCII characters.

No non-ASCII characters were found in your source files.

When I check the Problems tab, it looks like an error has occurred in mbed.h, but I don’t know why.
Could you please teach me?

Because your windows account name contains multibyte code.

Thank you for your advice.
I was able to solve the problem thanks to you.