Validation Error Language

Which validation error message are you referring to? Validation messages for individual fields can be changed by editing those fields in the form builder and selecting the Advanced tab.

The validation message that appears at the top of the form can be changed by creating a Spanish translation file for the Gravity Forms plugin using PO Edit. It's designed to be localized via translation files.

If you don't want to translate Gravity Forms you can also change the primary validation message with a simple code snippet you add to your themes functions.php file.

Here is what the code to change the validation message looks like:

<?php
add_filter("gform_validation_message", "change_message", 10, 2);
function change_message($message, $form){
return "Your Custom Validation Message Here";
}
?>

You would place that code in the functions.php file of your theme.

You can't change the text via CSS. It's in the markup and you have to use the filter or a translation file to change it.

Most likely you just need to remove the <?php ?> from around the snippet when you add it to your functions.php file because those already exist. Just configure/add this part.

add_filter("gform_validation_message", "change_message", 10, 2);
function change_message($message, $form){
return "Your Custom Validation Message Here";
}