diff --git a/wp-includes/class-wp-theme.php b/wp-includes/class-wp-theme.php
index 39ce67393f..bdf3bdd2d9 100644
--- a/wp-includes/class-wp-theme.php
+++ b/wp-includes/class-wp-theme.php
@@ -282,7 +282,7 @@ final class WP_Theme implements ArrayAccess {
 				)
 			);
 			if ( ! file_exists( $this->theme_root ) ) { // Don't cache this one.
-				$this->errors->add( 'theme_root_missing', __( 'Error: The themes directory is either empty or does not exist. Please check your installation.' ) );
+				$this->errors->add( 'theme_root_missing', __( '<strong>Error</strong>: The themes directory is either empty or does not exist. Please check your installation.' ) );
 			}
 			return;
 		} elseif ( ! is_readable( $this->theme_root . '/' . $theme_file ) ) {
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index 589a4256e7..4ca79af098 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -1600,7 +1600,7 @@ function do_feed() {
 	}
 
 	if ( ! has_action( "do_feed_{$feed}" ) ) {
-		wp_die( __( 'Error: This is not a valid feed template.' ), '', array( 'response' => 404 ) );
+		wp_die( __( '<strong>Error</strong>: This is not a valid feed template.' ), '', array( 'response' => 404 ) );
 	}
 
 	/**
diff --git a/wp-includes/version.php b/wp-includes/version.php
index ea0ffcc089..93639a1333 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.0-alpha-53117';
+$wp_version = '6.0-alpha-53118';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.