The 'wb_terms' table is being removed from the Wiki Replica databases. Please see Léa Lacroix's post on the wikidata mailing list [0] for additional details.
TL;DR summary: * May-June 2019, the Wikidata development team will drop the wb_terms table from the database in favor of a new optimized schema * Migration will start on 2019-05-29 * A test system will be available starting 2019-05-15 * Details are available in Phabricator [1]
[0]: https://lists.wikimedia.org/pipermail/wikidata/2019-April/012987.html [1]: https://phabricator.wikimedia.org/T221764
Bryan