facebook invalid scopes manage_pages. this message is only shown to developers
just remove manage_pages from the scope and it will work
<fb:login-button size="large"
scope="public_profile,email,pages_show_list,read_insights,manage_pages"
onlogin="checkLoginState();"> Click here to sync </fb:login-button>
to
<fb:login-button size="large"
scope="public_profile,email,pages_show_list,read_insights"
onlogin="checkLoginState();"> Click here to sync </fb:login-button>
just remove manage_page from scope attribute
<fb:login-button size="large"
scope="public_profile,email,pages_show_list,read_insights,manage_pages"
onlogin="checkLoginState();">
Click here to sync
</fb:login-button>
to
<fb:login-button size="large"
scope="public_profile,email,pages_show_list,read_insights"
onlogin="checkLoginState();">
Click here to sync
</fb:login-button>