Hi,
Last friday, I installed a new module (ERP embedded). Since this installation, products list is empty on frontend. I'm using Magento 2.4.2 on apache2/php 7.4.24.
I try to reindex but I have an error :
->bin/magento index:reindex
Catalog Search index process unknown error:
Item (Magento\CatalogInventory\Model\Stock\Status) with the same ID "1" already exists.
Single product is ok with direct url rewrite. I checked if urls rewrite existing for category, it's ok.
I used bin/magento setup:upgrade to update database, no error, all its ok.
I cleared and purged cache. I restarted elasticsearch.
I tried to use a backup before installation of ERP module (products list was ok), but I have the same problem, products list didn't work ! I suppose its a problem with elasticsearch.
I forced search engine with in/magento config:set catalog/search/engine elasticsearch7 and I watched elasticsearch status.
curl http://localhost:9200 return :
{
"name" : "XXXXXX",
"cluster_name" : "elasticsearch",
"cluster_uuid" : "DTqi_5JvSAKmdPpmjJgmgg",
"version" : {
"number" : "7.15.0",
"build_flavor" : "default",
"build_type" : "deb",
"build_hash" : "79d65f6e357953a5b3cbcc5e2c7c21073d89aa29",
"build_date" : "2021-09-16T03:05:29.143308416Z",
"build_snapshot" : false,
"lucene_version" : "8.9.0",
"minimum_wire_compatibility_version" : "6.8.0",
"minimum_index_compatibility_version" : "6.0.0-beta1"
},
"tagline" : "You Know, for Search"
}On magento backend, connection with elasticsearch is ok.
What can I check ? I don't have anymore solution 
I don't find something on magento forum to help me.
Thanks you very much.