xdvipdfmx pdf_ref_obj() error with fontawesome

You can try

\newfontfamily{\FA}{[FontAwesome.otf]}

after loading the fontawesome package (a simple modification of the comment by Ulrike Fischer). In general, directories for type1 fonts should be removed from search paths for fontconfig. Type1 fonts are almost unusable as native fonts in XeTeX, except for very simple encoding.

Another solution is to reject type1 fonts.

Add this <glob>-line to /etc/fonts/fonts.conf like this (take care of the correct parent tags):

<fontconfig>
    <selectfont>
        <rejectfont>
            <glob>/usr/share/texlive/texmf-dist/fonts/type1/*</glob>
        </rejectfont>
    </selectfont>
</fontconfig>

Attention: The commentar in the fonts.conf file says you should use local.conf instead of this file. But it is not on my system.