Error getting Events listing - API Error: ERROR - HTTP Code = '403' What does this mean and what do I do?

[Anonymous]

I connected a Marketo campaign with a GoToWebinar campaign a few weeks ago. All of a sudden, our form stopped showing registrations. The Marketo / GoToWebinar campaign sync now says "Error getting Events listing - API Error: ERROR -> HTTP Code = '403'. I checked past campaigns, and they all repeat the same error message.

What is this and how do I fix it?

[Anonymous]

We got this as well, starting from yesterday afternoon. I just relogged in to GoToWebinar from the Admin screen and that seems to have resolved the error for us. 

[Anonymous]

That worked for us, too. Appreciate your help!