Server Company and Developer Company keep passing the buck

I want to upgrade my Magento to 2.4.2.

The Developer Company who is doing this upgrade asked me to ensure my server has ElasticSearch 7.9.2

The Server Company installed ElasticSearch 7.9.2 on my server (I can see this from: curl -X GET "localhost:9200")

The Development Company has created a staging site on my server, but they say it only has 7.7.0 on it (they are getting this from /opt/plesk/php/7.4/bin/php -dmemory_limit=-1 /usr/local/psa/var/modules/composer/composer.phar show elasticsearch/elasticsearch)

My Server Company says:

"We have managed to install elasticsearch version 7.9 and there must be some configuration changes that needs to be made under settings which we are not aware of and as priorly updated the configuration part needs to be check at developer end.
If there is any settings that needs to be tweak at the server end please provide us, if possible we will surely make the required changes. "

And my Developer Company says:

"We don't know how to install and configure the Elastic Search on your server.
As a server people they should have to know this stuff"

Can someone please let me know how this could/should be resolved?

Are you installing or managing the Magento, or is the developer company doing it? If the developer is doing the Magento work, and Magento requires Elasticsearch, I would have thought the developer personnel would be familiar with Elasticsearch at least well enough to install and configure it to work with Magento. That's how I think it should be resolved.

However, it sounds like that may not be the case, so I would not be surprised if you have to be the "Elasticsearch people" on this project. How good are your Elasticsearch skills? Do you have a sandbox or test environment where the upgraded Magento and associated Elasticsearch instance can be set up, configured, and tested?

Hi Bob,

Thank you for replying. My skills are zero when it comes to ElasticSearch. I had never even heard of it until the developer asked for it to be installed.
My original site was a template from TemplateMonster but they don't have a Magento developer who can take my site to 2.4.2, so I found another developer to do this for me. They have created a 2.4.2 site, called staging.mydomain.com, where I can see the things that aren't working, but this ElasticSearch version issue has been bouncing back and forth for the last couple of weeks.