[Plugin: Visual Form Builder] define('WP_DEBUG', TRUE);

“Notice” isn’t a bug. It is a warning. It means that the code is depending upon undefined behavior. Something labeled “Notice” pretty much always works, but might stop working at some time in the future. It isn’t an error, but might– might– become one sometime later. They are best cleaned up, but don’t panic about them.

just try work on site when is DEBUG == TRUE,
don’t work redirect
don’t work message after submit, don’t work form bulder.. etc…
?? that is a 10h work to fix that …

Best regards

But i must to say this is a best form builder plugin ?? for me.

And if you can add on select box some list of values like countries list or somting simple…

Yes, those debug messages can cause some things to break, depending upon where they show up.

just define variables
$variable = (!empty($value)) $value ? : NULL ;

just define variables
$variable = (!empty($value)) $value ? : NULL ;

Of course, that is what the Notice is telling should have been done. Still, the reason it is a “Notice” and not an “Error” is that the code does work, at least for now.