Last week Google had removed the quota notification within the request indexing feature in the Google Search Console fetch as Google feature. Within the Google Search Console, there is the ability to Fetch as Google and then submit the URL you fetched to the Google index for possible inclusion. In that submit feature, Google shows how many URL submissions remained from a monthly quota. Though the documentation still had the quota, the interface removed the quota notification.
When efforts were made to hit the quota, there was no specific message received. Whenever quota was hit, an error was received involving a read “an error has occurred, please try again later.” But it doesn’t mention when to try again or why there is an error. Nobody is sure whether it’s just an error and unrelated to the quota.
See the forum discussion at Twitter.