Overview of the Issue
Submitting the form in the secondary language fails. This producess the below console error:
xxxxx/wp-json?lang=es/contact-form-7/v1/contact-forms/XXX/feedback 404 (Not Found)
This issue occurs only when setting the language URL format to ”Language name added as a parameter“.
Workaround
This issue is fixed. Updating to the latest version solves it on your site, so you only need this workaround if you can’t update yet.
Add this code to the theme’s functions.php file, found in the ../wp-content/themes/theme-name/ folder:
add_filter( 'wpcf7_load_js', '__return_false' );
