Once a while I got hit by the following issue:
A g1-small VM instance is currently unavailable in the us-central1-a zone. Alternatively, you can try your request again with a different VM hardware configuration or at a later time. For more information, see the troubleshooting documentation.
The issue used to last at least one day and disappear after several days. As I was allowed to create such an instance in the desired region and pay for its usage, it makes no sense that I cannot start my server.
This is very inconvenience and I think it’s a major issue with many customers.