NC 17. I can't make it work. Error v1.4.0

[4y55]

CentOS Linux release 7.7.1908 (Core)

Using elasticsearch-6.8.0.rpm and readonlyrest-1.18.10_es6.8.0.zip

Nextcloud 17.0.2 Full text search 1.3.5 Full text search - Elasticsearch Platform 1.4.0 Full text search - Files 1.3.6

/etc/elasticsearch/readonlyrest.yml
readonlyrest:
    access_controle_rules:

       name: "Require HTTP Basic Auth"
       type: allow
       auth_key: nextcloud:nextcloud
       indices: ["nextcloud"]

/etc/elasticsearch/elasticsearch.yml xpack.security.enabled: false

sudo -u apache /usr/bin/php /var/www/html/occ fulltextsearch:test

.Testing your current setup: Creating mocked content provider. ok Testing mocked provider: get indexable documents. (2 items) ok Loading search platform. (Elasticsearch) ok Testing search platform. An unhandled exception has been thrown: Error: Wrong parameters for Elasticsearch\Common\Exceptions\ServerErrorResponseException([string $message [, long $code [, Throwable $previous = NULL]]]) in /var/www/html/apps/fulltextsearch_elasticsearch/vendor/elasticsearch/elasticsearch/src/Elasticsearch/Connections/Connection.php:666 Stack trace: #0 /var/www/html/apps/fulltextsearch_elasticsearch/vendor/elasticsearch/elasticsearch/src/Elasticsearch/Connections/Connection.php(666): Exception->__construct(NULL, 503) #1 /var/www/html/apps/fulltextsearch_elasticsearch/vendor/elasticsearch/elasticsearch/src/Elasticsearch/Connections/Connection.php(282): Elasticsearch\Connections\Connection->process5xxError(Array, Array, Array) #2 /var/www/html/apps/fulltextsearch_elasticsearch/vendor/react/promise/src/FulfilledPromise.php(25): Elasticsearch\Connections\Connection->Elasticsearch\Connections\{closure}(Array) #3 /var/www/html/apps/fulltextsearch_elasticsearch/vendor/guzzlehttp/ringphp/src/Future/CompletedFutureValue.php(55): React\Promise\FulfilledPromise->then(Object(Closure), NULL, NULL) #4 /var/www/html/apps/fulltextsearch_elasticsearch/vendor/guzzlehttp/ringphp/src/Core.php(341): GuzzleHttp\Ring\Future\CompletedFutureValue->then(Object(Closure), NULL, NULL) #5 /var/www/html/apps/fulltextsearch_elasticsearch/vendor/elasticsearch/elasticsearch/src/Elasticsearch/Connections/Connection.php(299): GuzzleHttp\Ring\Core::proxy(Object(GuzzleHttp\Ring\Future\CompletedFutureArray), Object(Closure)) #6 /var/www/html/apps/fulltextsearch_elasticsearch/vendor/elasticsearch/elasticsearch/src/Elasticsearch/Connections/Connection.php(177): Elasticsearch\Connections\Connection->Elasticsearch\Connections\{closure}(Array, Object(Elasticsearch\Connections\Connection), Object(Elasticsearch\Transport), Array) #7 /var/www/html/apps/fulltextsearch_elasticsearch/vendor/elasticsearch/elasticsearch/src/Elasticsearch/Transport.php(112): Elasticsearch\Connections\Connection->performRequest('HEAD', '/', Array, NULL, Array, Object(Elasticsearch\Transport)) #8 /var/www/html/apps/fulltextsearch_elasticsearch/vendor/elasticsearch/elasticsearch/src/Elasticsearch/Client.php(1530): Elasticsearch\Transport->performRequest('HEAD', '/', Array, NULL, Array) #9 /var/www/html/apps/fulltextsearch_elasticsearch/vendor/elasticsearch/elasticsearch/src/Elasticsearch/Client.php(146): Elasticsearch\Client->performRequest(Object(Elasticsearch\Endpoints\Ping)) #10 /var/www/html/apps/fulltextsearch_elasticsearch/lib/Platform/ElasticSearchPlatform.php(176): Elasticsearch\Client->ping() #11 /var/www/html/apps/fulltextsearch/lib/Command/Test.php(300): OCA\FullTextSearch_ElasticSearch\Platform\ElasticSearchPlatform->testPlatform() #12 /var/www/html/apps/fulltextsearch/lib/Command/Test.php(157): OCA\FullTextSearch\Command\Test->testLoadingPlatform(Object(Symfony\Component\Console\Output\ConsoleOutput)) #13 /var/www/html/3rdparty/symfony/console/Command/Command.php(255): OCA\FullTextSearch\Command\Test->execute(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput)) #14 /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)) #15 /var/www/html/3rdparty/symfony/console/Application.php(908): OC\Core\Command\Base->run(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput)) #16 /var/www/html/3rdparty/symfony/console/Application.php(269): Symfony\Component\Console\Application->doRunCommand(Object(OCA\FullTextSearch\Command\Test), Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput)) #17 /var/www/html/3rdparty/symfony/console/Application.php(145): Symfony\Component\Console\Application->doRun(Object(Symfony\Component\Console\Input\ArgvInput), Object(Symfony\Component\Console\Output\ConsoleOutput)) #18 /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)) #19 /var/www/html/console.php(97): OC\Console\Application->run() #20 /var/www/html/occ(11): require_once('/var/www/html/c...') #21 {main}[root@localhost ~]#

Can anyone help me identify what's wrong? Thanks.