What type of action are you receiving this error on?
It’s most likely that you’re running into an API behavior issue.
For example, on the Shopify API if you attempt to look at an order that’s more than 60 days in the past with the standard access token it will throw a 404 error - even though the order exists.
You may be running into a access limitation or possibly the event ID just doesn’t line up with a corresponding resource on that API.