If you come across an error in Android 6.0 Marshmallow that says: "To keep going, the Google needs permission to access some things on your device", this is how you resolve it:

This error is related to use of Android Text-To-Speech engine and this is what the error message looks like:

To fix this issue, go to Settings, General, Apps, then select: Google App:

Click on Permissions option and you'll see the following screen:

Check permission for Microphone and go back to app that originally gave you an error.

This will resolve the issue.

If you want to see these instructions step by step, here is a video:

https://www.youtube.com/watch?v=tLxFvIfehYg

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If the issue present itself like this:

In this case, a much easier way to fix the problem would be to click on 'Continue' button and when you see a dialog that asks: "Allow Google App to Record Audio?", simple check "Never ask again" and press 'Allow' button.