I get an exception in wbformatvalue when trying to edit statements on certain Wikidata items:
mw1207 wikidatawiki 1.28.0-wmf.15 exception ERROR: [V7S85wpAANIAAHtaRLQAAACC] /w/api.php?action=wbformatvalue&format=json&datavalue=%7B%22value%22%3A%7B%22value%22%3A%7B%22entity-type%22%3A%22item%22%2C%22numeric-id%22%3A11299%7D%2C%22type%22%3A%22wikibase-entityid%22%2C%22error%22%3A%22serialization+is+required+for+constructing+a+EntityId+and+must+be+a+string%22%7D%2C%22type%22%3A%22undeserializable%22%7D&options=%7B%22lang%22%3A%22en%22%7D&generate=text%2Fplain&property=P131 InvalidArgumentException from line 49 of /srv/mediawiki/php-1.28.0-wmf.15/extensions/Wikidata/extensions/Wikibase/lib/includes/DataValueFactory.php: {"exception_id":"V7S85wpAANIAAHtaRLQAAACC"} [Exception InvalidArgumentException] (/srv/mediawiki/php-1.28.0-wmf.15/extensions/Wikidata/extensions/Wikibase/lib/includes/DataValueFactory.php:49) #0 /srv/mediawiki/php-1.28.0-wmf.15/extensions/Wikidata/extensions/Wikibase/lib/includes/DataValueFactory.php(79): DataValues\DataValueFactory->newDataValue(string, array) #1 /srv/mediawiki/php-1.28.0-wmf.15/extensions/Wikidata/extensions/Wikibase/repo/includes/Api/FormatSnakValue.php(191): DataValues\DataValueFactory->newFromArray(array) #2 /srv/mediawiki/php-1.28.0-wmf.15/extensions/Wikidata/extensions/Wikibase/repo/includes/Api/FormatSnakValue.php(98): Wikibase\Repo\Api\FormatSnakValue->decodeDataValue(string) #3 /srv/mediawiki/php-1.28.0-wmf.15/includes/api/ApiMain.php(1435): Wikibase\Repo\Api\FormatSnakValue->execute() #4 /srv/mediawiki/php-1.28.0-wmf.15/includes/api/ApiMain.php(508): ApiMain->executeAction() #5 /srv/mediawiki/php-1.28.0-wmf.15/includes/api/ApiMain.php(479): ApiMain->executeActionWithErrorHandling() #6 /srv/mediawiki/php-1.28.0-wmf.15/api.php(83): ApiMain->execute() #7 /srv/mediawiki/w/api.php(3): include(string) #8 {main} Caused by: [Exception Deserializers\Exceptions\UnsupportedTypeException] (/srv/mediawiki/php-1.28.0-wmf.15/extensions/Wikidata/vendor/data-values/serialization/src/Deserializers/DataValueDeserializer.php:108) #0 /srv/mediawiki/php-1.28.0-wmf.15/extensions/Wikidata/vendor/data-values/serialization/src/Deserializers/DataValueDeserializer.php(98): DataValues\Deserializers\DataValueDeserializer->assertHasSupportedType() #1 /srv/mediawiki/php-1.28.0-wmf.15/extensions/Wikidata/vendor/data-values/serialization/src/Deserializers/DataValueDeserializer.php(93): DataValues\Deserializers\DataValueDeserializer->assertCanDeserialize() #2 /srv/mediawiki/php-1.28.0-wmf.15/extensions/Wikidata/extensions/Wikibase/lib/includes/DataValueFactory.php(47): DataValues\Deserializers\DataValueDeserializer->deserialize(array) #3 /srv/mediawiki/php-1.28.0-wmf.15/extensions/Wikidata/extensions/Wikibase/lib/includes/DataValueFactory.php(79): DataValues\DataValueFactory->newDataValue(string, array) #4 /srv/mediawiki/php-1.28.0-wmf.15/extensions/Wikidata/extensions/Wikibase/repo/includes/Api/FormatSnakValue.php(191): DataValues\DataValueFactory->newFromArray(array) #5 /srv/mediawiki/php-1.28.0-wmf.15/extensions/Wikidata/extensions/Wikibase/repo/includes/Api/FormatSnakValue.php(98): Wikibase\Repo\Api\FormatSnakValue->decodeDataValue(string) #6 /srv/mediawiki/php-1.28.0-wmf.15/includes/api/ApiMain.php(1435): Wikibase\Repo\Api\FormatSnakValue->execute() #7 /srv/mediawiki/php-1.28.0-wmf.15/includes/api/ApiMain.php(508): ApiMain->executeAction() #8 /srv/mediawiki/php-1.28.0-wmf.15/includes/api/ApiMain.php(479): ApiMain->executeActionWithErrorHandling() #9 /srv/mediawiki/php-1.28.0-wmf.15/api.php(83): ApiMain->execute() #10 /srv/mediawiki/w/api.php(3): include(string) #11 {main}
https://www.wikidata.org/wiki/Q7588566
(other items are not a problem for me, but surely there are other affected items)