How to remove crx required proof missing error when installing crx browser extension?

Question

Google Chrome

Hello.
I want to make an extension for the Chrome browser for users of my site.

When installing, I get an error:

package invalid crx required proof missing

What needs to be corrected/changed?

My manfest.json

{
  "manifest_version": 2,
  "name": "test",
  "version": "1.0.0",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": ["content.js"]
    }
  ],
    "browser_action": {
    "default_icon": "favicon.ico"
  }
}

In content.js , the usual output is an alert message.

I go in the browser "Additionally - extensions - turn on developer mode, pack"

After that, I get a crx file, upload it to my site, call it like this: It

<a href="./script.crx">Install</a>

downloads, starts installing and displays the error "package is invalid crx required proof missing"

I read all sorts of articles, but I did not find anything worthwhile that could solve the problem.

Answer 1

The only thing I came across is that I need the crx3 version, but I didn’t find how to do it in an adequate way.
But it's not certain that this will solve the problem.
Or is this integration only available after publishing in the chrome extension store?

Answer 2

version 3 - manifest_version: 3, and further tweak the work with the API in acc. with 3rd manifest.
About installation from the site and like this - forget it. Only from the store, only the extension published there.