0👍
I figured it out!
When creating my project, I followed some random tutorial.
In the tutorial, I installed Vuex manually with npm, but it didn’t add it to the package.json file.
Now I added Vuex here manually:
"dependencies": {
"vue": "^3.2.13",
"vuex": "4.1.0"
},
I run npm install and npm run serve again…
and it works perfectly.
Source:stackexchange.com