Preview is not showing anything in android studio due to a error : I wrote a code for a android app.

There are other questions also like this. But still my problem is not solved

When I installed android studio preview was working very well. But now, the preview is not showing anything. There is a error, given in the image's link below.

https://drive.google.com/open?id=1F_9DlMh9F9HpNw6LN5jnY_5htf-qQVET

That image is my Preview Panel(Or, Whatever we call that)

Firstly I was thinking that this error is only for my current project. But when I opened a existing project, the error was still there.

Though, App is working well in mobile device.

But as the preview is showing my productivity is decreasing.

Please Help me getting rid of this error?