PHP Catchable fatal error

Hi,

WPMU upgradet, now: 9.1.1 version.

Error in PHP:

PHP Catchable fatal error: Object of class WP_Error could not be converted to string in C:xampphtdocswp-includescategory-template.php on line 71

The line 71

BEFORE UPGRADING: $chain .= ‘term_id ) . ‘” title=”‘ . sprintf( __( “View all posts in %s” ), $parent->cat_name ) . ‘”>’.$name.’‘ . $separator;

AFTER UPGRADING: $chain .= ‘term_id ) . ‘” title=”‘ . esc_attr( sprintf( __( “View all posts in %s” ), $parent->cat_name ) ) . ‘”>’.$name.’‘ . $separator;

Calling esc_attr() caused the problem ?

Please advice me.

Thanks a lot,

Michel