[Solved]-react router app hosted on firebase issues 404 error only when trying to access route via address bar-Reactjs

I had this problem too - I fixed it by configuring my app as a single page app. When you originally did firebase init you could have selected this as an option. Now, you can do that by manually changing your firebase.json file.

You want to add this to your firebase.json

"rewrites": [
  {
    "source": "**",
    "destination": "/index.html"
  }
]

so your firebase.json will look something like this

{
  "hosting": {
    "target": "your-app-name",
    "public": "your-build-directory",
    "rewrites": [
      {
        "source": "**",
        "destination": "/index.html"
      }
    ]
  }
}