# Property ‘x’ does not exist on type … – Promise syntax – TS2339

I met a problem I didn’t understand with Typescript. I found another topics with that kind of problem but even that i dont know how to resolve my problem.
I can console.log userCredential.user.metadata.b easily, but even that I got a error: Property ‘b’ does not exist on type ‘UserMetadata’. Can u explain me what here is wrong?

Here the part of code

<pre>
.then(userCredential => {
const creationTime: number = userCredential.user.metadata.b; // <-here is a problem
console.log('creationTinme', creationTime);
this.handleAuthentication(
userCredential.user.email,
userCredential.user.uid,
'xxx',
creationTime