Ticket #45401: 45401.diff

src/wp-includes/class-wp-query.php

@@ -4000 +4000 @@
                         $content = str_replace( "\n<!--nextpage-->", '<!--nextpage-->', $content );
                         $content = str_replace( "<!--nextpage-->\n", '<!--nextpage-->', $content );
 
+                        // Remove the nextpage block delimiters, to avoid invalid block structures in the split content.
+                        $content = str_replace( '<!-- wp:nextpage -->', '', $content );
+                        $content = str_replace( '<!-- /wp:nextpage -->', '', $content );
+
                         // Ignore nextpage at the beginning of the content.
                         if ( 0 === strpos( $content, '<!--nextpage-->' ) )
                                 $content = substr( $content, 15 );