diff -r 3d4e9c994f10 -r a86126ab1dd4 wp/wp-includes/customize/class-wp-customize-theme-control.php
--- a/wp/wp-includes/customize/class-wp-customize-theme-control.php	Tue Oct 22 16:11:46 2019 +0200
+++ b/wp/wp-includes/customize/class-wp-customize-theme-control.php	Tue Dec 15 13:49:49 2020 +0100
@@ -57,13 +57,13 @@
 	 * @since 4.2.0
 	 */
 	public function content_template() {
-		/* translators: %s: theme name */
+		/* translators: %s: Theme name. */
 		$details_label = sprintf( __( 'Details for theme: %s' ), '{{ data.theme.name }}' );
-		/* translators: %s: theme name */
+		/* translators: %s: Theme name. */
 		$customize_label = sprintf( __( 'Customize theme: %s' ), '{{ data.theme.name }}' );
-		/* translators: %s: theme name */
+		/* translators: %s: Theme name. */
 		$preview_label = sprintf( __( 'Live preview theme: %s' ), '{{ data.theme.name }}' );
-		/* translators: %s: theme name */
+		/* translators: %s: Theme name. */
 		$install_label = sprintf( __( 'Install and preview theme: %s' ), '{{ data.theme.name }}' );
 		?>
 		<# if ( data.theme.active ) { #>
@@ -84,36 +84,157 @@
 
 			<div class="theme-author">
 			<?php
-				/* translators: Theme author name */
+				/* translators: Theme author name. */
 				printf( _x( 'By %s', 'theme author' ), '{{ data.theme.author }}' );
 			?>
 			</div>
 
 			<# if ( 'installed' === data.theme.type && data.theme.hasUpdate ) { #>
-				<div class="update-message notice inline notice-warning notice-alt" data-slug="{{ data.theme.id }}">
-					<p>
+				<# if ( data.theme.updateResponse.compatibleWP && data.theme.updateResponse.compatiblePHP ) { #>
+					<div class="update-message notice inline notice-warning notice-alt" data-slug="{{ data.theme.id }}">
+						<p>
+							<?php
+							if ( is_multisite() ) {
+								_e( 'New version available.' );
+							} else {
+								printf(
+									/* translators: %s: "Update now" button. */
+									__( 'New version available. %s' ),
+									'<button class="button-link update-theme" type="button">' . __( 'Update now' ) . '</button>'
+								);
+							}
+							?>
+						</p>
+					</div>
+				<# } else { #>
+					<div class="update-message notice inline notice-error notice-alt" data-slug="{{ data.theme.id }}">
+						<p>
+							<# if ( ! data.theme.updateResponse.compatibleWP && ! data.theme.updateResponse.compatiblePHP ) { #>
+								<?php
+								printf(
+									/* translators: %s: Theme name. */
+									__( 'There is a new version of %s available, but it doesn&#8217;t work with your versions of WordPress and PHP.' ),
+									'{{{ data.theme.name }}}'
+								);
+								if ( current_user_can( 'update_core' ) && current_user_can( 'update_php' ) ) {
+									printf(
+										/* translators: 1: URL to WordPress Updates screen, 2: URL to Update PHP page. */
+										' ' . __( '<a href="%1$s">Please update WordPress</a>, and then <a href="%2$s">learn more about updating PHP</a>.' ),
+										self_admin_url( 'update-core.php' ),
+										esc_url( wp_get_update_php_url() )
+									);
+									wp_update_php_annotation( '</p><p><em>', '</em>' );
+								} elseif ( current_user_can( 'update_core' ) ) {
+									printf(
+										/* translators: %s: URL to WordPress Updates screen. */
+										' ' . __( '<a href="%s">Please update WordPress</a>.' ),
+										self_admin_url( 'update-core.php' )
+									);
+								} elseif ( current_user_can( 'update_php' ) ) {
+									printf(
+										/* translators: %s: URL to Update PHP page. */
+										' ' . __( '<a href="%s">Learn more about updating PHP</a>.' ),
+										esc_url( wp_get_update_php_url() )
+									);
+									wp_update_php_annotation( '</p><p><em>', '</em>' );
+								}
+								?>
+							<# } else if ( ! data.theme.updateResponse.compatibleWP ) { #>
+								<?php
+								printf(
+									/* translators: %s: Theme name. */
+									__( 'There is a new version of %s available, but it doesn&#8217;t work with your version of WordPress.' ),
+									'{{{ data.theme.name }}}'
+								);
+								if ( current_user_can( 'update_core' ) ) {
+									printf(
+										/* translators: %s: URL to WordPress Updates screen. */
+										' ' . __( '<a href="%s">Please update WordPress</a>.' ),
+										self_admin_url( 'update-core.php' )
+									);
+								}
+								?>
+							<# } else if ( ! data.theme.updateResponse.compatiblePHP ) { #>
+								<?php
+								printf(
+									/* translators: %s: Theme name. */
+									__( 'There is a new version of %s available, but it doesn&#8217;t work with your version of PHP.' ),
+									'{{{ data.theme.name }}}'
+								);
+								if ( current_user_can( 'update_php' ) ) {
+									printf(
+										/* translators: %s: URL to Update PHP page. */
+										' ' . __( '<a href="%s">Learn more about updating PHP</a>.' ),
+										esc_url( wp_get_update_php_url() )
+									);
+									wp_update_php_annotation( '</p><p><em>', '</em>' );
+								}
+								?>
+							<# } #>
+						</p>
+					</div>
+				<# } #>
+			<# } #>
+
+			<# if ( ! data.theme.compatibleWP || ! data.theme.compatiblePHP ) { #>
+				<div class="notice notice-error notice-alt"><p>
+					<# if ( ! data.theme.compatibleWP && ! data.theme.compatiblePHP ) { #>
 						<?php
-						if ( is_multisite() ) {
-							_e( 'New version available.' );
-						} else {
+						_e( 'This theme doesn&#8217;t work with your versions of WordPress and PHP.' );
+						if ( current_user_can( 'update_core' ) && current_user_can( 'update_php' ) ) {
+							printf(
+								/* translators: 1: URL to WordPress Updates screen, 2: URL to Update PHP page. */
+								' ' . __( '<a href="%1$s">Please update WordPress</a>, and then <a href="%2$s">learn more about updating PHP</a>.' ),
+								self_admin_url( 'update-core.php' ),
+								esc_url( wp_get_update_php_url() )
+							);
+							wp_update_php_annotation( '</p><p><em>', '</em>' );
+						} elseif ( current_user_can( 'update_core' ) ) {
 							printf(
-								/* translators: %s: "Update now" button */
-								__( 'New version available. %s' ),
-								'<button class="button-link update-theme" type="button">' . __( 'Update now' ) . '</button>'
+								/* translators: %s: URL to WordPress Updates screen. */
+								' ' . __( '<a href="%s">Please update WordPress</a>.' ),
+								self_admin_url( 'update-core.php' )
+							);
+						} elseif ( current_user_can( 'update_php' ) ) {
+							printf(
+								/* translators: %s: URL to Update PHP page. */
+								' ' . __( '<a href="%s">Learn more about updating PHP</a>.' ),
+								esc_url( wp_get_update_php_url() )
+							);
+							wp_update_php_annotation( '</p><p><em>', '</em>' );
+						}
+						?>
+					<# } else if ( ! data.theme.compatibleWP ) { #>
+						<?php
+						_e( 'This theme doesn&#8217;t work with your version of WordPress.' );
+						if ( current_user_can( 'update_core' ) ) {
+							printf(
+								/* translators: %s: URL to WordPress Updates screen. */
+								' ' . __( '<a href="%s">Please update WordPress</a>.' ),
+								self_admin_url( 'update-core.php' )
 							);
 						}
 						?>
-					</p>
-				</div>
+					<# } else if ( ! data.theme.compatiblePHP ) { #>
+						<?php
+						_e( 'This theme doesn&#8217;t work with your version of PHP.' );
+						if ( current_user_can( 'update_php' ) ) {
+							printf(
+								/* translators: %s: URL to Update PHP page. */
+								' ' . __( '<a href="%s">Learn more about updating PHP</a>.' ),
+								esc_url( wp_get_update_php_url() )
+							);
+							wp_update_php_annotation( '</p><p><em>', '</em>' );
+						}
+						?>
+					<# } #>
+				</p></div>
 			<# } #>
 
 			<# if ( data.theme.active ) { #>
 				<div class="theme-id-container">
 					<h3 class="theme-name" id="{{ data.section }}-{{ data.theme.id }}-name">
-						<?php
-						/* translators: %s: theme name */
-						printf( __( '<span>Previewing:</span> %s' ), '{{ data.theme.name }}' );
-						?>
+						<span><?php _ex( 'Previewing:', 'theme' ); ?></span> {{ data.theme.name }}
 					</h3>
 					<div class="theme-actions">
 						<button type="button" class="button button-primary customize-theme" aria-label="<?php echo esc_attr( $customize_label ); ?>"><?php _e( 'Customize' ); ?></button>
@@ -124,7 +245,11 @@
 				<div class="theme-id-container">
 					<h3 class="theme-name" id="{{ data.section }}-{{ data.theme.id }}-name">{{ data.theme.name }}</h3>
 					<div class="theme-actions">
-						<button type="button" class="button button-primary preview-theme" aria-label="<?php echo esc_attr( $preview_label ); ?>" data-slug="{{ data.theme.id }}"><?php _e( 'Live Preview' ); ?></button>
+						<# if ( data.theme.compatibleWP && data.theme.compatiblePHP ) { #>
+							<button type="button" class="button button-primary preview-theme" aria-label="<?php echo esc_attr( $preview_label ); ?>" data-slug="{{ data.theme.id }}"><?php _e( 'Live Preview' ); ?></button>
+						<# } else { #>
+							<button type="button" class="button button-primary disabled" aria-label="<?php echo esc_attr( $preview_label ); ?>"><?php _e( 'Live Preview' ); ?></button>
+						<# } #>
 					</div>
 				</div>
 				<div class="notice notice-success notice-alt"><p><?php _ex( 'Installed', 'theme' ); ?></p></div>
@@ -132,7 +257,11 @@
 				<div class="theme-id-container">
 					<h3 class="theme-name" id="{{ data.section }}-{{ data.theme.id }}-name">{{ data.theme.name }}</h3>
 					<div class="theme-actions">
-						<button type="button" class="button button-primary theme-install preview" aria-label="<?php echo esc_attr( $install_label ); ?>" data-slug="{{ data.theme.id }}" data-name="{{ data.theme.name }}"><?php _e( 'Install &amp; Preview' ); ?></button>
+						<# if ( data.theme.compatibleWP && data.theme.compatiblePHP ) { #>
+							<button type="button" class="button button-primary theme-install preview" aria-label="<?php echo esc_attr( $install_label ); ?>" data-slug="{{ data.theme.id }}" data-name="{{ data.theme.name }}"><?php _e( 'Install &amp; Preview' ); ?></button>
+						<# } else { #>
+							<button type="button" class="button button-primary disabled" aria-label="<?php echo esc_attr( $install_label ); ?>" disabled><?php _e( 'Install &amp; Preview' ); ?></button>
+						<# } #>
 					</div>
 				</div>
 			<# } #>