Magento 2: Error with ElasticSearch after upgrading from 2.2.5 to 2.3.4

Question

I just recently upgraded a Magento project from 2.2.5 to 2.3.4, went in the Catalog Search configuration to change to use Elastic Search 6, tested connection successfully. However when trying to run reindex

bin/magento indexer:reindex catalogsearch_fulltext

I got this error:

Undefined index: elasticsearch6 in /app/vendor/magento/module-elasticsearch/Elasticsearch5/Model/Adapter/FieldMapper/ProductFieldMapperProxy.php on line 44

Does anyone know how to resolve this? Why is it trying to call from Elasticsearch5 module?

Answer 1

Under Stores -> Attributes -> Product select Color. Then go to store front properties tab and set the following:

Use in Search: No

Use In Search Results Layered Navigation No

Then run the following two commands:

bin/magento cache:clean

bin/magento indexer:reindex catalogsearch_fulltext

You may get this warning for another attribute after doing this change. The key for this is a filterable attributes could be only Boolean, price and select and multiselect.