I have a Google App Engine app which currently displays:
Over Quota
This application is temporarily over its serving quota. Please try again later.
I have a billed account. When I check my quotas, I am well under all limits. I have about 10,000 tasks sitting in the queue waiting to be processed - but even that is well under the 1,000,000,000 limit.
I have no idea how to debug this as all I get is the message that I'm over quota which, according to my quota stats, is not true.
Here is a dump of the quota stats (sorry about the formatting):
It is because of the frontend instance hours eaten up by the task queue. I thought I had configured the app to use one backend instance, but apparently not: GAE: Queues, Quotas and backend instances