Why won't it pass a function to a child React component rendered by React Router as a prop?

Question

I'm trying to pass a function to a child component so that I can return some data to save in the root component's state.

<Route exact path="/signin" component={Signin}
        render={(props)=>(<Signin {...props} updateAppState={this.updateAppState}></Signin>)}></Route>}

Above it shows how I pass the function to the component as a prop. Below is the function itself:

updateAppState = () => {
    console.log("Reached")
    this.setState({loggedin:true});
  }   

Here is how I am attempting to use the function in the child component:

    signIn = () => {

    Axios.post(`http://localhost:3001/mongooose/checkUser`,this.state)
      .then(data=>data.data=='Session started'?(alert(data.data),console.log(this.props),this.props.updateAppState()):alert(data.data))
      .catch(err=>console.log(err))

  }