While implementing emp API in LWC to subscribe the platform event I  find out that there is small issue in sample code snipit given in documentation.
Issue is in handleSubscribe method in js below is the code given in documentation:

handleSubscribe() {
        // Callback invoked whenever a new event message is received
        const messageCallback = function(response) {
            console.log('New message received : ', JSON.stringify(response));
            // Response contains the payload of the new message received
        };

        // Invoke subscribe method of empApi. Pass reference to messageCallback
        subscribe(this.channelName, -1, messageCallback).then(response => {
            // Response contains the subscription information on successful subscribe call
            console.log('Successfully subscribed to : ', JSON.stringify(response.channel));
            this.subscription = response;
            this.toggleSubscribeButton(true);
        });
    }

 Correction is required in messageCallback method which should be as below:

const messageCallback = (response) => {
        console.log('New message received : ', JSON.stringify(response));
        this.payload = JSON.stringify(response);
        console.log('this.payload: ' + this.payload);
        // Response contains the payload of the new message received
    };

We have to use arrow function as it does not have its own scope.  

Hi Guys,

We are a plan to migrate the sandbox with lightning before that we run the  'Readiness Check' report but it's not yet received to my mail?

Already enabled the email Deliverability Access level to All email. But still facing the problem.

Is there any permission setting need to check? 

Please check and help me?

While implementing emp API in LWC to subscribe the platform event I  find out that there is small issue in sample code snipit given in documentation.
Issue is in handleSubscribe method in js below is the code given in documentation:

handleSubscribe() {
        // Callback invoked whenever a new event message is received
        const messageCallback = function(response) {
            console.log('New message received : ', JSON.stringify(response));
            // Response contains the payload of the new message received
        };

        // Invoke subscribe method of empApi. Pass reference to messageCallback
        subscribe(this.channelName, -1, messageCallback).then(response => {
            // Response contains the subscription information on successful subscribe call
            console.log('Successfully subscribed to : ', JSON.stringify(response.channel));
            this.subscription = response;
            this.toggleSubscribeButton(true);
        });
    }

 Correction is required in messageCallback method which should be as below:

const messageCallback = (response) => {
        console.log('New message received : ', JSON.stringify(response));
        this.payload = JSON.stringify(response);
        console.log('this.payload: ' + this.payload);
        // Response contains the payload of the new message received
    };

We have to use arrow function as it does not have its own scope.