Android Studio Manifest URI is not registered

Question

I am getting an error all over my Android Project, this project I have been working on for several months now and all of a sudden all my android projects have errors.

I get a "cannot find symbol R" when I call something like:

 setContentView(R.layout.activity_driver_login);

This was never a problem before.

In My android Manifest file I get an error "URI is not registered"

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"

I have this problem as well:

and when I click on the App button that I referenced in the picture, I get this.

.

Why did this happen all of a sudden and how can I fix this? This isn't specific to this project, this problem occurs on all of my other projects and even on a separate machine I get these errors.

Note I have tried rebuilding the project, but nothing changes.

Answer 1

So this isn't exactly an answer to the above question, but what I did do that got me back to work, was that I put the code on another machine that I installed Android studio on and the Code worked, and I can compile without any errors. So my feeling is that if you come across the problem mentioned above, then backup your code as it is, uninstall and reinstall Android Studio.