ElasticSearch is not able to index authorities no configured at koha as default, rebuild gets this error Can't locate object method "type" via package "Can't call method "tag" on an undefined value at /usr/share/koha/lib/C4/Heading.pm line 71. " (perhaps you forgot to load "Can't call method "tag" on an undefined value at /usr/share/koha/lib/C4/Heading.pm line 71. "?) at rebuild_elasticsearch.pl line 312. If a customer has added a new authoriy like 147, ES is not able to index it, it is not a very common issue, but it could happen. Authorities at koha are hardcoded and you can 't add on web admin Kindest regards