Upgrade of megento 2.4
We planned to upgrade our Magento app from 2.2.7 to Magento 2.4 as there are many performance & security fixes with latest version. for that, we must have to install and configure Elasticsearch 7.6.x before upgrading to Magento 2.4.0.

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Clarence Parsons commented
I am glad to hear that you have fixed the Magento app. I am a website designer and Magento is easy for me to use it. I want to design a website that should be similar to https://youressayreviews.com/review-of-edubirdie-com-services/. It is my test and my clients want me to make it on Magento. I was so happy when my client told me to make it on Magento because I am very comfortable using it.
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Anonymous commented
New instances will not work with composer 2
The errors look like this:
Problem 1
- magento/composer-root-update-plugin is locked to version 1.0.0 and an update of this package was not requested.
- magento/composer-root-update-plugin 1.0.0 requires composer-plugin-api ^1.0 -> found composer-plugin-api[2.0.0] but it does not match the constraint.
Problem 2
- dealerdirect/phpcodesniffer-composer-installer is locked to version v0.5.0 and an update of this package was not requested.
- dealerdirect/phpcodesniffer-composer-installer v0.5.0 requires composer-plugin-api ^1.0 -> found composer-plugin-api[2.0.0] but it does not match the constraint.
Problem 3
- laminas/laminas-dependency-plugin 1.0.4 requires composer-plugin-api ^1.1 -> found composer-plugin-api[2.0.0] but it does not match the constraint.
- magento/product-community-edition 2.4.0 requires laminas/laminas-dependency-plugin ^1.0 -> satisfiable by laminas/laminas-dependency-plugin[1.0.4].
- magento/product-community-edition is locked to version 2.4.0 and an update of this package was not requested.
You are using Composer 2, which some of your plugins seem to be incompatible with. Make sure you update your plugins or report a plugin-issue to ask them to support Composer 2.
Installation failed, reverting ./composer.json and ./composer.lock to their original content.
Also I have spoken with a support agent who downgraded to Composer 1 but that triggers another error:
$ composer update
[UnexpectedValueException]
Unknown package has no name defined ([{"name":"2tvenom\/cborencode","version":"1.0.2","version_normalized":"1.0.2.0","source":{"type":"git","url":"https:\/\/github.com\/2tvenom\/CBOREncode.git","reference":"42aedccb861d01fc0554782348cc08f8ebf22332"},"dist":{"type":"zip","url":"https:\/\/api.github.com\/repos\/2
tvenom\/CBOREncode\/zipball\/42aedccb861d01fc0554782348cc08f8ebf22332","reference":"42aedccb861d01fc0554782348cc08f8ebf22332","shasum":""},"require":{"php":">=5.4.0"},"time":"2020-10-27T07:22:41+00:00","type":"library","installation-source":"dist","autoload":{"psr-0":{"CBOR":"src"}},"notification-url":"https:\/
\/packagist.org\/downloads\/The error continues with the whole list of Mage modules.