What can be the possible reason for this?
AWS does not have sufficient capacity in that availability zone
AWS zone mapping is changed for that user account
There is some issue with the host capacity on which the instance is launched
The user account has reached the maximum EC2 instance limit
Explanations:
AWS may not have sufficient capacity in the requested availability zone at the time of instance restart, leading to theInsufficientInstanceCapacityerror.
AWS zone mapping being changed for a user account is not a likely cause of this error. Zone mapping changes don’t trigger this specific error.
The host capacity issue usually applies to instances that are part of a specific hardware fleet. The error in this case is more likely related to zone capacity.
The instance limit being reached would result in a different error message, notInsufficientInstanceCapacity. This error pertains to availability zone capacity.
If I’m correct, the answer is:
AWS does not have sufficient capacity in that availability zone