Error when updating the form

Are you activate multi-site?

No, no multi-site,

And, by the way, i’m on wp_debug mode so it desapears when i disable it. But why does it give this error?

That’s because $wpdb->signups is empty.
https://github.com/dulabs/frontend-edit-profile/blob/master/fep.php#L404
And i’m still searching why this happen.

Can you tell me, your PHP version and WordPress Version?

My php version is 5.6

Hello
Use the global $wpdb object.

Search:

// Update the email address in signups, if present.
        if ($user->user_login && isset($_POST[ 'email' ]) && is_email($_POST[ 'email' ]) && $wpdb->get_var($wpdb->prepare("SELECT user_login FROM {$wpdb->signups} WHERE user_login = %s", $user->user_login))) {
            $wpdb->query($wpdb->prepare("UPDATE {$wpdb->signups} SET user_email = %s WHERE user_login = %s", $_POST[ 'email' ], $user_login));
        }

And Replace with:

// Update the email address in signups, if present.
		global $wpdb;
        if ($user->user_login && isset($_POST[ 'email' ]) && is_email($_POST[ 'email' ]) && $wpdb->get_var($wpdb->prepare("SELECT user_login FROM {$wpdb->signups} WHERE user_login = %s", $user->user_login))) {
            $wpdb->query($wpdb->prepare("UPDATE {$wpdb->signups} SET user_email = %s WHERE user_login = %s", $_POST[ 'email' ], $user_login));
        }

thank’s R.F., hope the developper will do this as soon as possible.

i added global $wpdb; but still get the error,
WordPress database error You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'WHERE user_login = 'WPUSER'' at line 1 for query SELECT user_login FROM WHERE user_login = 'WPUSER'

notice the repeated single quote at the end of the first WHERE. i dont see where this is coming from or if its part of the issue but when i comment out the above code, the error is not present.