Upgrade Standard Reserved Instance

I understand you're trying to upgrade your EC2 t2.large Standard Reserved Instance to a t2.xlarge, but you're encountering difficulties. Let me explain why this is happening and what options you have.

Reserved Instances (RIs) can be modified, but there are specific rules and limitations to be aware of:

1. For Standard RIs, you can modify the Availability Zone, scope, network platform, and instance size within the same instance family. In your case, changing from t2.large to t2.xlarge is within the same T2 family, so this should be possible.

2. The platform must be Linux/UNIX for instance size modifications.

3. Both the original and new Reserved Instance must have the same instance size footprint. The instance size footprint is determined by the normalization factor of the instance size and the number of instances.

4. You must have sufficient capacity for the new configuration.

If you're unable to make this modification, it could be due to one of these reasons:

1. The instance size footprint might not match. A t2.large has a normalization factor of 4, while a t2.xlarge has a factor of 8. You may need to adjust the number of instances to maintain the same footprint.

2. There might not be sufficient capacity for the t2.xlarge in your chosen Availability Zone.

3. Your Reserved Instance might be listed in the Reserved Instance Marketplace, which would prevent modifications.

If you can't modify your existing RI, you have a few options:

1. You could launch a new t2.xlarge instance and let your existing t2.large RI continue to provide a discount on other t2.large instances or smaller T2 instances.

2. You could wait for your current RI to expire and then purchase a new RI for the t2.xlarge.

3. If your workload permits, you could consider using a different instance family that might better suit your needs.

Remember, while you can't change the instance family of a Standard RI, Convertible RIs offer more flexibility for changing instance types across families, although they typically come at a higher cost.
Sources
Modify Reserved Instances - Amazon Elastic Compute Cloud
Amazon EC2 instance type changes - Amazon Elastic Compute Cloud