^^&&^^

Edit File: class-theme-installer-skin.php

<?php
/**
 * Upgrader API: Theme_Installer_Skin class
 *
 * @package WordPress
 * @subpackage Upgrader
 * @since 4.6.0
 */

/**
 * Theme Installer Skin for the WordPress Theme Installer.
 *
 * @since 2.8.0
 * @since 4.6.0 Moved to its own file from wp-admin/includes/class-wp-upgrader-skins.php.
 *
 * @see WP_Upgrader_Skin
 */
class Theme_Installer_Skin extends WP_Upgrader_Skin {
	public $api;
	public $type;
	public $url;
	public $overwrite;

private $is_downgrading = false;

/**
	 * Constructor.
	 *
	 * Sets up the theme installer skin.
	 *
	 * @since 2.8.0
	 *
	 * @param array $args
	 */
	public function __construct( $args = array() ) {
		$defaults = array(
			'type'      => 'web',
			'url'       => '',
			'theme'     => '',
			'nonce'     => '',
			'title'     => '',
			'overwrite' => '',
		);
		$args     = wp_parse_args( $args, $defaults );

$this->type      = $args['type'];
		$this->url       = $args['url'];
		$this->api       = isset( $args['api'] ) ? $args['api'] : array();
		$this->overwrite = $args['overwrite'];

parent::__construct( $args );
	}

/**
	 * Performs an action before installing a theme.
	 *
	 * @since 2.8.0
	 */
	public function before() {
		if ( ! empty( $this->api ) ) {
			$this->upgrader->strings['process_success'] = sprintf(
				$this->upgrader->strings['process_success_specific'],
				$this->api->name,
				$this->api->version
			);
		}
	}

/**
	 * Hides the `process_failed` error when updating a theme by uploading a zip file.
	 *
	 * @since 5.5.0
	 *
	 * @param WP_Error $wp_error WP_Error object.
	 * @return bool True if the error should be hidden, false otherwise.
	 */
	public function hide_process_failed( $wp_error ) {
		if (
			'upload' === $this->type &&
			'' === $this->overwrite &&
			$wp_error->get_error_code() === 'folder_exists'
		) {
			return true;
		}

return false;
	}

/**
	 * Performs an action following a single theme install.
	 *
	 * @since 2.8.0
	 */
	public function after() {
		if ( $this->do_overwrite() ) {
			return;
		}

if ( empty( $this->upgrader->result['destination_name'] ) ) {
			return;
		}

$theme_info = $this->upgrader->theme_info();
		if ( empty( $theme_info ) ) {
			return;
		}

$name       = $theme_info->display( 'Name' );
		$stylesheet = $this->upgrader->result['destination_name'];
		$template   = $theme_info->get_template();

$activate_link = add_query_arg(
			array(
				'action'     => 'activate',
				'template'   => urlencode( $template ),
				'stylesheet' => urlencode( $stylesheet ),
			),
			admin_url( 'themes.php' )
		);
		$activate_link = wp_nonce_url( $activate_link, 'switch-theme_' . $stylesheet );

$install_actions = array();

if ( current_user_can( 'edit_theme_options' ) && current_user_can( 'customize' ) && ! $theme_info->is_block_theme() ) {
			$customize_url = add_query_arg(
				array(
					'theme'  => urlencode( $stylesheet ),
					'return' => urlencode( admin_url( 'web' === $this->type ? 'theme-install.php' : 'themes.php' ) ),
				),
				admin_url( 'customize.php' )
			);

$install_actions['preview'] = sprintf(
				'<a href="%s" class="hide-if-no-customize load-customize">' .
				'<span aria-hidden="true">%s</span><span class="screen-reader-text">%s</span></a>',
				esc_url( $customize_url ),
				__( 'Live Preview' ),
				/* translators: Hidden accessibility text. %s: Theme name. */
				sprintf( __( 'Live Preview &#8220;%s&#8221;' ), $name )
			);
		}

$install_actions['activate'] = sprintf(
			'<a href="%s" class="activatelink">' .
			'<span aria-hidden="true">%s</span><span class="screen-reader-text">%s</span></a>',
			esc_url( $activate_link ),
			_x( 'Activate', 'theme' ),
			/* translators: Hidden accessibility text. %s: Theme name. */
			sprintf( _x( 'Activate &#8220;%s&#8221;', 'theme' ), $name )
		);

if ( is_network_admin() && current_user_can( 'manage_network_themes' ) ) {
			$install_actions['network_enable'] = sprintf(
				'<a href="%s" target="_parent">%s</a>',
				esc_url( wp_nonce_url( 'themes.php?action=enable&amp;theme=' . urlencode( $stylesheet ), 'enable-theme_' . $stylesheet ) ),
				__( 'Network Enable' )
			);
		}

if ( 'web' === $this->type ) {
			$install_actions['themes_page'] = sprintf(
				'<a href="%s" target="_parent">%s</a>',
				self_admin_url( 'theme-install.php' ),
				__( 'Go to Theme Installer' )
			);
		} elseif ( current_user_can( 'switch_themes' ) || current_user_can( 'edit_theme_options' ) ) {
			$install_actions['themes_page'] = sprintf(
				'<a href="%s" target="_parent">%s</a>',
				self_admin_url( 'themes.php' ),
				__( 'Go to Themes page' )
			);
		}

if ( ! $this->result || is_wp_error( $this->result ) || is_network_admin() || ! current_user_can( 'switch_themes' ) ) {
			unset( $install_actions['activate'], $install_actions['preview'] );
		} elseif ( get_option( 'template' ) === $stylesheet ) {
			unset( $install_actions['activate'] );
		}

/**
		 * Filters the list of action links available following a single theme installation.
		 *
		 * @since 2.8.0
		 *
		 * @param string[] $install_actions Array of theme action links.
		 * @param object   $api             Object containing WordPress.org API theme data.
		 * @param string   $stylesheet      Theme directory name.
		 * @param WP_Theme $theme_info      Theme object.
		 */
		$install_actions = apply_filters( 'install_theme_complete_actions', $install_actions, $this->api, $stylesheet, $theme_info );
		if ( ! empty( $install_actions ) ) {
			$this->feedback( implode( ' | ', (array) $install_actions ) );
		}
	}

/**
	 * Checks if the theme can be overwritten and outputs the HTML for overwriting a theme on upload.
	 *
	 * @since 5.5.0
	 *
	 * @return bool Whether the theme can be overwritten and HTML was outputted.
	 */
	private function do_overwrite() {
		if ( 'upload' !== $this->type || ! is_wp_error( $this->result ) || 'folder_exists' !== $this->result->get_error_code() ) {
			return false;
		}

$folder = $this->result->get_error_data( 'folder_exists' );
		$folder = rtrim( $folder, '/' );

$current_theme_data = false;
		$all_themes         = wp_get_themes( array( 'errors' => null ) );

foreach ( $all_themes as $theme ) {
			$stylesheet_dir = wp_normalize_path( $theme->get_stylesheet_directory() );

if ( rtrim( $stylesheet_dir, '/' ) !== $folder ) {
				continue;
			}

$current_theme_data = $theme;
		}

$new_theme_data = $this->upgrader->new_theme_data;

if ( ! $current_theme_data || ! $new_theme_data ) {
			return false;
		}

echo '<h2 class="update-from-upload-heading">' . esc_html__( 'This theme is already installed.' ) . '</h2>';

// Check errors for active theme.
		if ( is_wp_error( $current_theme_data->errors() ) ) {
			$this->feedback( 'current_theme_has_errors', $current_theme_data->errors()->get_error_message() );
		}

$this->is_downgrading = version_compare( $current_theme_data['Version'], $new_theme_data['Version'], '>' );

$is_invalid_parent = false;
		if ( ! empty( $new_theme_data['Template'] ) ) {
			$is_invalid_parent = ! in_array( $new_theme_data['Template'], array_keys( $all_themes ), true );
		}

$rows = array(
			'Name'        => __( 'Theme name' ),
			'Version'     => __( 'Version' ),
			'Author'      => __( 'Author' ),
			'RequiresWP'  => __( 'Required WordPress version' ),
			'RequiresPHP' => __( 'Required PHP version' ),
			'Template'    => __( 'Parent theme' ),
		);

$table  = '<table class="update-from-upload-comparison"><tbody>';
		$table .= '<tr><th></th><th>' . esc_html_x( 'Installed', 'theme' ) . '</th><th>' . esc_html_x( 'Uploaded', 'theme' ) . '</th></tr>';

$is_same_theme = true; // Let's consider only these rows.

foreach ( $rows as $field => $label ) {
			$old_value = $current_theme_data->display( $field, false );
			$old_value = $old_value ? (string) $old_value : '-';

$new_value = ! empty( $new_theme_data[ $field ] ) ? (string) $new_theme_data[ $field ] : '-';

if ( $old_value === $new_value && '-' === $new_value && 'Template' === $field ) {
				continue;
			}

$is_same_theme = $is_same_theme && ( $old_value === $new_value );

$diff_field     = ( 'Version' !== $field && $new_value !== $old_value );
			$diff_version   = ( 'Version' === $field && $this->is_downgrading );
			$invalid_parent = false;

if ( 'Template' === $field && $is_invalid_parent ) {
				$invalid_parent = true;
				$new_value     .= ' ' . __( '(not found)' );
			}

$table .= '<tr><td class="name-label">' . $label . '</td><td>' . wp_strip_all_tags( $old_value ) . '</td>';
			$table .= ( $diff_field || $diff_version || $invalid_parent ) ? '<td class="warning">' : '<td>';
			$table .= wp_strip_all_tags( $new_value ) . '</td></tr>';
		}

$table .= '</tbody></table>';

/**
		 * Filters the compare table output for overwriting a theme package on upload.
		 *
		 * @since 5.5.0
		 *
		 * @param string   $table              The output table with Name, Version, Author, RequiresWP, and RequiresPHP info.
		 * @param WP_Theme $current_theme_data Active theme data.
		 * @param array    $new_theme_data     Array with uploaded theme data.
		 */
		echo apply_filters( 'install_theme_overwrite_comparison', $table, $current_theme_data, $new_theme_data );

$install_actions = array();
		$can_update      = true;

$blocked_message  = '<p>' . esc_html__( 'The theme cannot be updated due to the following:' ) . '</p>';
		$blocked_message .= '<ul class="ul-disc">';

$requires_php = isset( $new_theme_data['RequiresPHP'] ) ? $new_theme_data['RequiresPHP'] : null;
		$requires_wp  = isset( $new_theme_data['RequiresWP'] ) ? $new_theme_data['RequiresWP'] : null;

if ( ! is_php_version_compatible( $requires_php ) ) {
			$error = sprintf(
				/* translators: 1: Current PHP version, 2: Version required by the uploaded theme. */
				__( 'The PHP version on your server is %1$s, however the uploaded theme requires %2$s.' ),
				PHP_VERSION,
				$requires_php
			);

$blocked_message .= '<li>' . esc_html( $error ) . '</li>';
			$can_update       = false;
		}

if ( ! is_wp_version_compatible( $requires_wp ) ) {
			$error = sprintf(
				/* translators: 1: Current WordPress version, 2: Version required by the uploaded theme. */
				__( 'Your WordPress version is %1$s, however the uploaded theme requires %2$s.' ),
				esc_html( wp_get_wp_version() ),
				$requires_wp
			);

$blocked_message .= '<li>' . esc_html( $error ) . '</li>';
			$can_update       = false;
		}

$blocked_message .= '</ul>';

if ( $can_update ) {
			if ( $this->is_downgrading ) {
				$warning = sprintf(
					/* translators: %s: Documentation URL. */
					__( 'You are uploading an older version of the installed theme. You can continue to install the older version, but be sure to <a href="%s">back up your database and files</a> first.' ),
					__( 'https://developer.wordpress.org/advanced-administration/security/backup/' )
				);
			} else {
				$warning = sprintf(
					/* translators: %s: Documentation URL. */
					__( 'You are updating a theme. Be sure to <a href="%s">back up your database and files</a> first.' ),
					__( 'https://developer.wordpress.org/advanced-administration/security/backup/' )
				);
			}

echo '<p class="update-from-upload-notice">' . $warning . '</p>';

$overwrite = $this->is_downgrading ? 'downgrade-theme' : 'update-theme';

$install_actions['overwrite_theme'] = sprintf(
				'<a class="button button-primary update-from-upload-overwrite" href="%s" target="_parent">%s</a>',
				wp_nonce_url( add_query_arg( 'overwrite', $overwrite, $this->url ), 'theme-upload' ),
				_x( 'Replace installed with uploaded', 'theme' )
			);
		} else {
			echo $blocked_message;
		}

$cancel_url = add_query_arg( 'action', 'upload-theme-cancel-overwrite', $this->url );

$install_actions['themes_page'] = sprintf(
			'<a class="button" href="%s" target="_parent">%s</a>',
			wp_nonce_url( $cancel_url, 'theme-upload-cancel-overwrite' ),
			__( 'Cancel and go back' )
		);

/**
		 * Filters the list of action links available following a single theme installation failure
		 * when overwriting is allowed.
		 *
		 * @since 5.5.0
		 *
		 * @param string[] $install_actions Array of theme action links.
		 * @param object   $api             Object containing WordPress.org API theme data.
		 * @param array    $new_theme_data  Array with uploaded theme data.
		 */
		$install_actions = apply_filters( 'install_theme_overwrite_actions', $install_actions, $this->api, $new_theme_data );

if ( ! empty( $install_actions ) ) {
			printf(
				'<p class="update-from-upload-expired hidden">%s</p>',
				__( 'The uploaded file has expired. Please go back and upload it again.' )
			);
			echo '<p class="update-from-upload-actions">' . implode( ' ', (array) $install_actions ) . '</p>';
		}

return true;
	}
}