When I run php bin/magento indexer:reindex I get the following error message from the Catalog Search indexer:
{"error":{"root_cause":[{"type":"mapper_parsing_exception","reason":"analyzer [sku] not found for field [sku]"}],"type":"mapper_parsing_exception","reason":"analyzer [sku] not found for field [sku]"},"status":400}
I have checked that elasticSearch 7 is connected and running. I have disabled a search autocomplete plugin (https://www.mageworx.com/magento-2-search-autocomplete-free.html) and that also did not resolve the issue.
I noticed some others had issues but mainly due to a mirasvit plugin which I do not have installed.
Best Answer
It might be related to your ElasticSearch installation or version.
Check if you're using ElasticSearch 7.9 as required and try to reset the indexes before run the reindex.