Bdtjtk

I tried upgrading my PHP version that works well with PHP 7.1.25 to 7.2 or 7.3.
My options page crashed, losing some in the database.
Wordpress version is 4.9.7.
Plugins: Tilesim (private) Elementor and Woocommrece (latest version 1.1.19)
Theme: child of 2017 with a single page.

I get the following warning:

``PHP Warning:  Cannot modify header information - headers already sent by (output started at .../wp-content/plugins/tilesim/ts_admin.php:300) in .../wp-includes/rest-api/class-wp-rest-server.php on line 1248``

Note: Google search shows that upgrade to 7.2 might be an issue

Since all the code is formed with input and textarea tags.
Any idea what might be the problem?

Here is the code for the options page that I tested
``

add_action('admin_init', 'register_tilesim_plugin_settings');



function register_tilesim_plugin_settings() {

    //register our settings

    register_setting( 'tilesim-option-group', 'ts_manufacture_name' );

    register_setting( 'tilesim-option-group', 'ts_manufacture_logo' );

    register_setting( 'tilesim-option-group', 'ts_manufacture_email' );

// board settings

    register_setting( 'tilesim-option-group', 'ts_online_help_pid' ); 

    register_setting( 'tilesim-option-group', 'ts_init_board_width' );

    register_setting( 'tilesim-option-group', 'ts_allowed_min_board_width' );

    register_setting( 'tilesim-option-group', 'ts_allowed_max_board_width' );

    register_setting( 'tilesim-option-group', 'ts_default_tile_size' ); // default tile size

    register_setting( 'tilesim-option-group', 'ts_rotateLR_image' ); 

    register_setting( 'tilesim-option-group', 'ts_rotateRL_image' ); 

    register_setting( 'tilesim-option-group', 'ts_eraser_image' ); 



// report settings

    register_setting( 'tilesim-option-group', 'ts_report_header_image' ); 

    register_setting( 'tilesim-option-group', 'ts_report_footer_image' ); 

    register_setting( 'tilesim-option-group', 'ts_report_title' ); 

    register_setting( 'tilesim-option-group', 'ts_report_sigtext' ); // signature text



// css settings

    register_setting( 'tilesim-option-group', 'ts_css' ); // css code

}









function ts_plugin_options() {

    if ( !current_user_can( 'manage_options' ) )

        wp_die( __( 'You do not have sufficient permissions to access this page.' ) );

        ts_options_page();

}





function ts_options_page(){

$labelStyle= "width:130px;display:inline-block;";

$labelTextareaStyle= "width:130px;display:inline-block;vertical-align: top;";

$logoInStyle = "width: 597px;text-align: right;direction:ltr";

$EmailInStyle = "text-align: left;";

?>

    <div class="wrap">

          <h2>Tilesim Settings</h2><br />



         <form action="options.php" method="post">

               <?php settings_fields( 'tilesim-option-group' );?>

               <?php do_settings_sections( 'tilesim' );?>

              <label style="<?php echo $labelStyle; ?>">Manufacture Name:</label>

                   <input type="text" name="ts_manufacture_name" value="<?php echo get_option( 'ts_manufacture_name' ); ?>" /><br />

              <label style="<?php echo $labelStyle; ?>">Manufacture Logo:</label>

                   <input style="<?php echo $logoInStyle ; ?>" type="text" name="ts_manufacture_logo" value="<?php echo get_option( 'ts_manufacture_logo' ); ?>" /><br />

              <label style="<?php echo $labelStyle; ?>">Manufacture Email:</label>

                   <input style="<?php echo $EmailInStyle ; ?>" type="text" name="ts_manufacture_email" value="<?php echo get_option( 'ts_manufacture_email' ); ?>" /><br />

<h3 style="font-weight: 500;">Board settings</h3>

               <label style="<?php echo $labelStyle; ?>">Help Post ID:</label>

                   <input type="text" name="ts_online_help_pid" value="<?php echo get_option( 'ts_online_help_pid' ); ?>" /><br />

               <label style="<?php echo $labelStyle; ?>">Initial Board Width:</label>

                   <input type="text" name="ts_init_board_width" value="<?php echo get_option( 'ts_init_board_width' ); ?>" />

               <label style="<?php echo $labelStyle; ?>">Default Tile Size:(cm)</label>

                   <input type="text" name="ts_default_tile_size" value="<?php echo get_option( 'ts_default_tile_size' ); ?>" /><br />

               <label style="<?php echo $labelStyle; ?>">Min Board Width:</label>

                   <input type="text" name="ts_allowed_min_board_width" value="<?php echo get_option( 'ts_allowed_min_board_width' ); ?>" />

               <label style="<?php echo $labelStyle; ?>">Max Board Width:</label>

                   <input type="text" name="ts_allowed_max_board_width" value="<?php echo get_option( 'ts_allowed_max_board_width' ); ?>" /><br />

               <label style="<?php echo $labelStyle; ?>">Left to Right image:</label>

                   <input style="<?php echo $logoInStyle ; ?>" type="text" name="ts_rotateLR_image" value="<?php echo get_option( 'ts_rotateLR_image' ); ?>" /><br />

               <label style="<?php echo $labelStyle; ?>">Right to left image:</label>

                   <input style="<?php echo $logoInStyle ; ?>" type="text" name="ts_rotateRL_image" value="<?php echo get_option( 'ts_rotateRL_image' ); ?>" /><br />

               <label style="<?php echo $labelStyle; ?>">Eraser image:</label>

                   <input style="<?php echo $logoInStyle ; ?>" type="text" name="ts_eraser_image" value="<?php echo get_option( 'ts_eraser_image' ); ?>" /><br />



<h3 style="font-weight: 500;">Report settings</h3>



               <label style="<?php echo $labelStyle; ?>">Header Image:</label>

                   <input style="<?php echo $logoInStyle ; ?>" type="text" name="ts_report_header_image" 

                          value="<?php echo get_option( 'ts_report_header_image' ); ?>" /><br />

               <label style="<?php echo $labelStyle; ?>">Footer Image:</label>

                   <input style="<?php echo $logoInStyle ; ?>" type="text" name="ts_report_footer_image" 

                          value="<?php echo get_option( 'ts_report_footer_image' ); ?>" /><br />

               <label style="<?php echo $labelStyle; ?>">Report Title:</label>

                   <input style="<?php echo $logoInStyle ; ?>" type="text" name="ts_report_title" value="<?php echo get_option( 'ts_report_title' ); ?>" /><br />

               <label style="<?php echo $labelTextareaStyle; ?>">Report Signature:</label>

                   <textarea style="direction:rtl;text-align:right" type="textarea" name="ts_report_sigtext" cols="81" rows="4"><?php echo esc_html(trim(get_option( 'ts_report_sigtext' ))); ?></textarea>

<h3 style="font-weight: 500;">Css settings</h3>

<p>Note: No css validation is provided. CSS loads last. Harmful code removed.</p>



               <label style="<?php echo $labelTextareaStyle; ?>">CSS code:</label>

                   <textarea style="direction:ltr;text-align:left" type="textarea" name="ts_css" cols="81" rows="8"><?php echo esc_html(trim(get_option( 'ts_css' ))); ?></textarea>



               <?php submit_button();?> 

          </form>

   </div>

<?php

}





?>

``