Това Magento просто не съм очаквал, че е толкова бъгаво НЕЩО:

tail -f log/exception.log

Проблем N1:

[2020-09-07 14:45:00] main.CRITICAL: No alive nodes found in your cluster {"exception":"[object] (Elasticsearch\\Common\\Exceptions\\NoNodesAvailableException(code: 0): No alive nodes found in your cluster at /var/www/magento-live/vendor/elasticsearch/elasticsearch/src/Elasticsearch/ConnectionPool/StaticNoPingConnectionPool.php:53)"} []

Решение N1: /etc/init.d/elasticsearch restart

Проблем N2:

[2020-09-07 14:45:40] main.CRITICAL: catalog_product index does not exist yet. Make sure everything is reindexed. {"report_id":"f54001a12b0abb106e826862e505a03f8ea41f3591d4663631a4315af8285696","exception":"[object] (LogicException(code: 0): catalog_product index does not exist yet. Make sure everything is reindexed. at /var/www/magento-live/vendor/smile/elasticsuite/src/module-elasticsuite-core/Index/IndexOperation.php:117)"} []

Решение N2: php magento indexer:reindex или Reindex от админ панела

Проблем N3:
# php magento indexer:reindex
Design Config Grid index has been rebuilt successfully in 00:00:00
Customer Grid index has been rebuilt successfully in 00:00:00
Category Products index has been rebuilt successfully in 00:00:01
Product Categories index has been rebuilt successfully in 00:00:00
Catalog Rule Product index has been rebuilt successfully in 00:00:00
Product EAV index has been rebuilt successfully in 00:00:01
Stock index has been rebuilt successfully in 00:00:00
Product Price index has been rebuilt successfully in 00:00:01
Catalog Product Rule index has been rebuilt successfully in 00:00:00
Catalog Search indexer process unknown error:
{"error":{"root_cause":[{"type":"cluster_block_exception","reason":"blocked by: [FORBIDDEN/12/index read-only / allow delete (api)];"}],"type":"cluster_block_exception","reason":"blocked by: [FORBIDDEN/12/index read-only / allow delete (api)];"},"status":403}
Google Product Removal Feed index has been rebuilt successfully in 00:00:00
Google Product Feed index has been rebuilt successfully in 00:00:00
ElasticSuite Category Indexing indexer process unknown error:
{"error":{"root_cause":[{"type":"cluster_block_exception","reason":"blocked by: [FORBIDDEN/12/index read-only / allow delete (api)];"}],"type":"cluster_block_exception","reason":"blocked by: [FORBIDDEN/12/index read-only / allow delete (api)];"},"status":403}
ElasticSuite Thesaurus Indexing indexer process unknown error:
{"error":{"root_cause":[{"type":"cluster_block_exception","reason":"blocked by: [FORBIDDEN/12/index read-only / allow delete (api)];"}],"type":"cluster_block_exception","reason":"blocked by: [FORBIDDEN/12/index read-only / allow delete (api)];"},"status":403}

Решение N3:
curl -XPUT -H "Content-Type: application/json" http://localhost:9200/_all/_settings -d '{"index.blocks.read_only_allow_delete": null}'