https.createServer not working REST server

Question

I am trying to create a HTTPS server with express and typescript and here is my code, for some reason the https.createserver seems to never be working and i get this error:

UnhandledPromiseRejectionWarning: Error: error:0909006C:PEM routines:get_name:no start line

but i am new in this and i have found 0 answers online.

On my App.ts in the contructor i have:

this.express= express();
const key = fs.readFileSync('/home/user/private.key');
const cert = fs.readFileSync('/home/user/file.csr');
this.middlewares();
this.routes();
this.app = https.createServer({ key, cert }, this.express);

And the function listen that initializes the app:

listen() {
    this.app.listen(3000);
    console.log('Server on port', 3000);
}

On my index.ts

import { App } from './app'
import { connect } from './database'

function main() {
    const app = new App(4001);
    app.listen();
}

main();