Hello.

This fix will be exist in future updates of Booking Calendar (in update 8.4.1).

So firstly please update your Booking Calendar to the latest update 8.4 and then make this customization.
You can request the new update of Booking Calendar on this page: https://wpbookingcalendar.com/request-update/

Please make this customizations.

1) Please open this file ../wp-content/plugins/{Booking Calendar Folder}/js/client.js

( you can check how to edit files in WordPress menu in this article https://wpbookingcalendar.com/faq/how-edit-file-in-wp-menu/ )

then find this code:

function showMessageUnderElement( element , errorMessage , message_type) { if(typeof( bk_form_step_click ) == 'function') { bk_form_step_click(); // rollback to 1st step, if system will show warning and booking form is using this customization: in the Exmaple #2 here: https://wpbookingcalendar.com/faq/customize-booking-form-for-having-several-steps-of-reservation/ }

and replace it to this code:

function showMessageUnderElement( element , errorMessage , message_type) { //FixIn: 8.4.0.2 // if(typeof( bk_form_step_click ) == 'function') { // bk_form_step_click(); // rollback to 1st step, if system will show warning and booking form is using this customization: in the Exmaple #2 here: https://wpbookingcalendar.com/faq/customize-booking-form-for-having-several-steps-of-reservation/ // }

2) Then find this code:

// Show Error Message in Booking Form at Front End function showErrorMessage( element , errorMessage) { if(typeof( bk_form_step_click ) == 'function') { bk_form_step_click(); // rollback to 1st step, if system will show warning and booking form is using this customization: in the Exmaple #2 here: https://wpbookingcalendar.com/faq/customize-booking-form-for-having-several-steps-of-reservation/ }

and replace it to this code:

// Show Error Message in Booking Form at Front End function showErrorMessage( element , errorMessage) { //FixIn: 8.4.0.2 // if(typeof( bk_form_step_click ) == 'function') { // bk_form_step_click(); // rollback to 1st step, if system will show warning and booking form is using this customization: in the Exmaple #2 here: https://wpbookingcalendar.com/faq/customize-booking-form-for-having-several-steps-of-reservation/ // }

3) Then find this code:

// Check fields at form and then send request function mybooking_submit( submit_form , bk_type, wpdev_active_locale){

and replace it to this code:

// Check fields at form and then send request function mybooking_submit( submit_form , bk_type, wpdev_active_locale){ //FixIn: 8.4.0.2 var is_error = wpbc_check_errors_in_booking_form( bk_type ); if ( is_error ) { return false; }

4) Then add this code to the bottom of this file:

//FixIn: 8.4.0.2
/**
 * Check errors in booking form  fields, and show warnings if some errors exist.
 * Check  errors,  like not selected dates or not filled requred form  fields, or not correct entering email or phone fields,  etc...
 *
 * @param bk_type  int (ID of booking resource)
 */
function wpbc_check_errors_in_booking_form( bk_type ) {

    var is_error_in_field = false;  // By default all  is good - no error

    var my_form = jQuery( '#booking_form' + bk_type );

    if ( my_form.length ) {

        // Pseudo-selector that get form elements input , textarea , select, button...
        my_form.find( ':input' ).each( function( index, el ) {

            // Skip some elements
            var skip_elements = [ 'hidden', 'button' ];

            if (  -1 == skip_elements.indexOf( jQuery( el ).attr( 'type' ) )  ){

				// Check Calendar Dates Selection
                if ( ( 'date_booking' + bk_type ) == jQuery( el ).attr( 'name' ) ) {

                    // Show Warning only  if the calendar visible ( we are at step with  calendar)
                    if (  ( jQuery( '#calendar_booking4' ).is( ':visible' )  ) && ( '' == jQuery( el ).val() )  ) {
						showMessageUnderElement( '#date_booking' + bk_type, message_verif_selectdts, '' );
						is_error_in_field = true;    // Error
                    }
                }

                // Check only visible elements at this step
                if ( jQuery( el ).is( ':visible' )  ){

					// Is Required
					if ( jQuery( el ).hasClass( 'wpdev-validates-as-required' ) ){

						// Checkboxes
						if ( 'checkbox' == jQuery( el ).attr( 'type' ) ){

							if ( !jQuery( el ).is( ':checked' ) ){
								showErrorMessage( el, message_verif_requred_for_check_box );
								is_error_in_field = true;    // Error
							}

							// Radio boxes
						} else if ( 'radio' == jQuery( el ).attr( 'type' ) ){

							if ( !jQuery( ':radio[name="' + jQuery( el ).attr( 'name' ) + '"]', my_form ).is( ':checked' ) ){
								showErrorMessage( el, message_verif_requred_for_radio_box );
								is_error_in_field = true;    // Error
							}

							// Other elements
						} else {

							var inp_value = jQuery( el ).val();

							if ( '' === jQuery.trim( inp_value ) ){
								showErrorMessage( el, message_verif_requred );
								is_error_in_field = true;    // Error
							}
						}
					}

					// Validate Email
					if ( jQuery( el ).hasClass( 'wpdev-validates-as-email' ) ){
						var inp_value = jQuery( el ).val();
						inp_value = inp_value.replace( /^\s+|\s+$/gm, '' );                // Trim  white space //FixIn: 5.4.5
						var reg = /^([A-Za-z0-9_\-\.\+])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,})$/;
						if ( (inp_value != '') && (reg.test( inp_value ) == false) ){
							showErrorMessage( el, message_verif_emeil );
							is_error_in_field = true;    // Error
						}
					}

					var classList = jQuery( el ).attr( 'class' );

					if ( classList ){

						classList = classList.split( /\s+/ );

                        jQuery.each( classList, function ( cl_index, cl_item ){

                            ////////////////////////////////////////////////////////////////////////////////////////////

                            // Validate field value as "Date"   [CSS class - 'validate_as_digit']
                            if ( 'validate_as_date' === cl_item ) {

                                // Valid values: 09-25-2018, 09/25/2018, 09-25-2018,  31-9-1918  ---   m/d/Y, m.d.Y, m-d-Y, d/m/Y, d.m.Y, d-m-Y
                                var regex = new RegExp( '^[0-3]?\\d{1}[\\/\\.\\-]+[0-3]?\\d{1}[\\/\\.\\-]+[0-2]+\\d{3}$' );       // Check for Date 09/25/2018
                                var message_verif_phone = 'This field must be valid date like this ' + '09/25/2018';
                                var inp_value = jQuery( el ).val();

                                if (  ( inp_value != '' ) && ( regex.test( inp_value ) == false )  ){
                                    showErrorMessage( el, message_verif_phone );
                                    is_error_in_field = true;    // Error
                                }
                            }

                            ////////////////////////////////////////////////////////////////////////////////////////////

                            // Validate field value as "DIGIT"   [CSS class - 'validate_as_digit']
                            if ( 'validate_as_digit' === cl_item ) {

                                var regex = new RegExp( '^[0-9]+\\.?[0-9]*$' );       // Check for digits
                                var message_verif_phone = 'This field must contain only digits';
                                var inp_value = jQuery( el ).val();

                                if (  ( inp_value != '' ) && ( regex.test( inp_value ) == false )  ){
                                    showErrorMessage( el, message_verif_phone );
                                    is_error_in_field = true;    // Error
                                }
                            }

                            ////////////////////////////////////////////////////////////////////////////////////////////

                            // Validate field value as "Phone" number or any other valid number wth specific number of digits [CSS class - 'validate_digit_8' || 'validate_digit_10' ]
                            var is_validate_digit = cl_item.substring( 0, 15 );

                            // Check  if class start  with 'validate_digit_'
                            if ( 'validate_digit_' === is_validate_digit ){

                                // Get  number of digit in class: validate_digit_8 => 8 or validate_digit_10 => 10
                                var digits_to_check = parseInt( cl_item.substring( 15 ) );

                                // Check  about any errors in
                                if ( !isNaN( digits_to_check ) ){

                                    var regex = new RegExp( '^\\d{' + digits_to_check + '}$' );       // We was valid it as parseInt - only integer variable - digits_to_check
                                    var message_verif_phone = 'This field must contain ' + digits_to_check + ' digits';
                                    var inp_value = jQuery( el ).val();

									if (  ( inp_value != '' ) && ( regex.test( inp_value ) == false )  ){
                                        showErrorMessage( el, message_verif_phone );
                                        is_error_in_field = true;    // Error
                                    }
                                }
                            }

                            ////////////////////////////////////////////////////////////////////////////////////////////

                        });
    				}
                }
			}
        } );

	}
    return is_error_in_field;
}

Please do not forget to clear browser cache before testing these changes.

B) Your booking form confuiguration the JavaScript section which is relative to steps forwardnign must be configred like this at the Booking > Settings > Form page:

function bk_calendar_step_click( el ){ 
  var br_id = jQuery( el ).closest( 'form' ).find( 'input[name^="bk_type"]' ).val(); 
  
  
  var is_error = wpbc_check_errors_in_booking_form( br_id );
  if ( is_error ) { return false; }
  
  if ( br_id != undefined ) { 
    jQuery( "#booking_form" + br_id + " .bk_calendar_step" ).css({"display":"none"}); 
    jQuery( "#booking_form" + br_id + " .bk_form_step" ).css({"display":"block"}); 
  } else { 
    jQuery(".bk_calendar_step" ).css({"display":"none"}); 
    jQuery(".bk_form_step" ).css({"display":"block"}); 
  } 
} 
function bk_form_step_click( el ){ 
  var br_id = jQuery( el ).closest( 'form' ).find( 'input[name^="bk_type"]' ).val(); 
  
  var is_error = wpbc_check_errors_in_booking_form( br_id );
  if ( is_error ) { return false; }
  
  if ( br_id != undefined ) { 
    jQuery( "#booking_form" + br_id + " .bk_calendar_step" ).css({"display":"block"}); 
    jQuery( "#booking_form" + br_id + " .bk_form_step" ).css({"display":"none"}); 
    makeScroll( "#bklnk" + br_id ); 
  } else { 
    jQuery(".bk_calendar_step" ).css({"display":"block"}); 
    jQuery(".bk_form_step" ).css({"display":"none"}); 
  } 
} 

Kind Regards.

Hello.
Can you send screenshots of where exactly you see incorrect today date in calendar ?
Please send it to the support @ wpbookingcalendar.com
Also please send scree shot of WordPress > Settings General page, as well.
Kind Regards.