Why is there an error when installing vuex? - vue.js

Question

Tell me, I understand that there is a problem in the versions, but how to solve it?
I have tried:
npm cache clean --force commands
npm install -g npm-install-peers
npm install --legacy-peer-deps
Install with npm install --save-dev vuex#next gives me this error
My package.json file:
"name": "",
"version": "0.1.0",
"private": true,
"scripts": {
"serve": "vue-cli-service serve",
"build": "vue-cli-service build",
"lint": "vue-cli-service lint",
"serve:standalone": "vue-cli-service serve --mode standalone"
},
"dependencies": {
"core-js": "^3.6.5",
"devextreme": "21.2.5",
"devextreme-vue": "21.2.5",
"single-spa-vue": "^2.1.0",
"vue": "^2.6.11"
},
"devDependencies": {
"#storybook/vue": "^6.4.14",
"#vue/cli": "^4.5.15",
"#vue/cli-plugin-babel": "~4.5.0",
"#vue/cli-plugin-eslint": "~4.5.0",
"#vue/cli-service": "~4.5.0",
"babel-eslint": "^10.1.0",
"eslint": "^6.7.2",
"node-sass": "^6.0.1",
"sass-loader": "^10",
"eslint-plugin-vue": "^6.2.2",
"vue-cli-plugin-single-spa": "~3.1.2",
"vue-template-compiler": "^2.6.11"
},
"eslintConfig": {
"root": true,
"env": {
"node": true
},
"extends": [
"plugin:vue/essential",
"eslint:recommended"
],
"parserOptions": {
"parser": "babel-eslint"
},
"rules": {}
},
"browserslist": [
"> 1%",
"last 2 versions",
"not dead"
]

Answer 1

That is because you're trying to install Vuex#4, which is only compatible with Vue#3. However, your project is using Vue#2 instead.
You will need to decide which Vue version you want to use. Since you mentioned that you only want to use Vue2, you need to install the Vuex#3 instead:
npm install vuex#3