Fulltext search index error IllegalArgumentException

[GammaPi]

It occurs no matter external storage or group folder indexing are enabled or not.

Elasticsearch Version: 6.6.1

App Version:
Full text search 1.2.5
Full text search - Elasticsearch Platform 1.2.4
Full text search - Files 1.2.6

Nextcloud Version:15.0.5

│ Message: java.lang.IllegalArgumentException: java.lang.IllegalArgumentExcept
│ ion: field [content] not present as part of path [attachment.content]
│
└──

x:first result ## c/v:prec/next result ## b:last result

f:first error ## h/j:prec/next error ## d:delete error ## l:last error

q:quit ## p:pause

An unhandled exception has been thrown:
Error: Call to a member function getUID() on null in /var/www/html/lib/private/Share20/Manager.php:1427
Stack trace:
#0 /var/www/html/custom_apps/files_fulltextsearch/lib/Service/LocalFilesService.php(162): OC\Share20\Manager->getAccessList(Object(OC\Files\Node\Folder), true, true)
#1 /var/www/html/custom_apps/files_fulltextsearch/lib/Service/FilesService.php(667): OCA\Files_FullTextSearch\Service\LocalFilesService->getShareUsersFromFile(Object(OC\Files\Node\Folder), Array)
#2 /var/www/html/custom_apps/files_fulltextsearch/lib/Service/FilesService.php(596): OCA\Files_FullTextSearch\Service\FilesService->updateShareNames(Object(OCA\Files_FullTextSearch\Model\FilesDocument), Object(OC\Files\Node\Folder))
#3 /var/www/html/custom_apps/files_fulltextsearch/lib/Service/FilesService.php(570): OCA\Files_FullTextSearch\Service\FilesService->updateDocumentAccess(Object(OCA\Files_FullTextSearch\Model\FilesDocument), Object(OC\Files\Node\Folder))
#4 /var/www/html/custom_apps/files_fulltextsearch/lib/Service/FilesService.php(551): OCA\Files_FullTextSearch\Service\FilesService->updateFilesDocumentFromFile(Object(OCA\Files_FullTextSearch\Model\FilesDocument), Object(OC\Files\Node\Folder))
#5 /var/www/html/custom_apps/files_fulltextsearch/lib/Service/FilesService.php(445): OCA\Files_FullTextSearch\Service\FilesService->updateFilesDocument(Object(OCA\Files_FullTextSearch\Model\FilesDocument))
#6 /var/www/html/custom_apps/files_fulltextsearch/lib/Provider/FilesProvider.php(246): OCA\Files_FullTextSearch\Service\FilesService->generateDocument(Object(OCA\Files_FullTextSearch\Model\FilesDocument))
#7 /var/www/html/custom_apps/fulltextsearch/lib/Service/IndexService.php(314): OCA\Files_FullTextSearch\Provider\FilesProvider->fillIndexDocument(Object(OCA\Files_FullTextSearch\Model\FilesDocument))
#8 /var/www/html/custom_apps/fulltextsearch/lib/Service/IndexService.php(194): OCA\FullTextSearch\Service\IndexService->indexDocuments(Object(OCA\FullTextSearch_ElasticSearch\Platform\ElasticSearchPlatform), Object(OCA\Files_FullTextSearch\Provider\FilesProvider), Array, Object(OCA\FullTextSearch\Model\IndexOptions))
#9 /var/www/html/custom_apps/fulltextsearch/lib/Command/Index.php(408): OCA\FullTextSearch\Service\IndexService->indexProviderContentFromUser(Object(OCA\FullTextSearch_ElasticSearch\Platform\ElasticSearchPlatform), Object(OCA\Files_FullTextSearch\Provider\FilesProvider), 'tjx', Object(OCA\FullTextSearch\Model\IndexOptions))
#10 /var/www/html/custom_apps/fulltextsearch/lib/Command/Index.php(272): OCA\FullTextSearch\Command\Index->indexProvider(Object(OCA\Files_FullTextSearch\Provider\FilesProvider), Object(OCA\FullTextSearch\Model\IndexOptions))
#11 /var/www/html/3rdparty/symfony/console/Command/Command.php(255): OCA\FullTextSearch\Command\Index->execute(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#12 /var/www/html/core/Command/Base.php(166): Symfony\Component\Console\Command\Command->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#13 /var/www/html/3rdparty/symfony/console/Application.php(946): OC\Core\Command\Base->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#14 /var/www/html/3rdparty/symfony/console/Application.php(248): Symfony\Component\Console\Application->doRunCommand(Object(OCA\FullTextSearch\Command\Index), Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#15 /var/www/html/3rdparty/symfony/console/Application.php(148): Symfony\Component\Console\Application->doRun(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#16 /var/www/html/lib/private/Console/Application.php(213): Symfony\Component\Console\Application->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput))
#17 /var/www/html/console.php(96): OC\Console\Application->run()
#18 /var/www/html/occ(11): require_once('/var/www/html/c...')

[GammaPi]

Problem fixed after upgrading to 16.0.1