Thank you very much for entering.
I have a registration form that works correctly, belongs to the Ultimate Wordpress plugin. The problem is when I put that form in a modal, because when sending the form, the error appears: "Invalid Nonce." on an all white screen.
The HTML of the modal and Form is as follows:
<div class="modal fade" id="modalRegisterForm" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true">
<div class="modal-dialog" role="document">
<div class="modal-content">
<div class="modal-header text-center">
<h4 class="modal-title w-100 font-weight-bold">Registro</h4>
<button type="button" class="close" data-dismiss="modal" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>
<form method="post">
<div class="modal-body mx-3">
<div class="md-form mb-5" data-key="first_name">
<i class="fa fa-user prefix grey-text"></i>
<input autocomplete="off" class="form-control validate" type="text" name="first_name-121" id="first_name-121" value="" placeholder="" data-validate="" data-key="first_name">
<label data-error="Incorrecto" data-success="Correcto" for="orangeForm-name">Ingrese su nombre</label>
</div>
<div class="md-form mb-5" data-key="user_email">
<i class="fa fa-envelope prefix grey-text"></i>
<input type="email" autocomplete="off" type="text" name="user_email-121" id="user_email-121" value="" placeholder="" data-validate="unique_email" data-key="user_email" class="form-control validate">
<label data-error="Incorrecto" data-success="Correcto" for="orangeForm-email">Ingrese su email</label>
</div>
<div class="md-form mb-4" data-key="user_password">
<i class="fa fa-lock prefix grey-text"></i>
<input type="password" autocomplete="new-password" name="user_password-121" id="user_password-121" value="" placeholder="" data-validate="" data-key="user_password" class="form-control validate">
<label data-error="Incorrecto" data-success="Correcto" for="orangeForm-pass">Ingrese una contraseña</label>
</div>
<div class="md-form mb-4" data-key="confirm_user_password">
<i class="fa fa-lock prefix grey-text"></i>
<input type="password" autocomplete="new-password" name="confirm_user_password-121" id="confirm_user_password-121" value="" placeholder="" data-validate="" data-key="confirm_user_password" class="form-control validate">
<label data-error="Incorrecto" data-success="Correcto" for="orangeForm-pass">Repita su contraseña</label>
</div>
<input type="hidden" name="form_id" id="form_id_121" value="121">
</div>
<div class="modal-footer d-block justify-content-center">
<input type="submit" value="Registrar" class="um-button" id="register-submit-btn" style="margin-top: 14px;">
</div>
</form>
</div>
</div>
</div>ID: 121 corresponds to the ID of the form created with the plugin.
What can be done about it to solve it? Thank you very much already.