You can't share a VPC subnet
Scenario
When you attempt to use Amazon RAM to share a VPC subnet with another account, the
sharing operation succeeds. However, the consuming account shows LIMIT
EXCEEDED
for that resource in the Amazon RAM console.
Cause
Some individual resource types have service-specific restrictions separate from
the restrictions enforced by Amazon RAM. Some of those restrictions can effectively
prevent sharing even if you haven't reached one of the restrictions in Amazon RAM. Limits
are an example of these restrictions. Amazon Virtual Private Cloud (Amazon VPC) limits the number of subnets
that you can share with another individual account. If you try to share a subnet
with a consuming account that already contains the maximum number of subnets, then
that consuming accounts displays LIMIT EXCEEDED
in the console for that
resource. For more information about this limit, see Amazon VPC Quotas
– VPC sharing in the Amazon Virtual Private Cloud User
Guide.
To address this, first check for other resource shares that might be sharing the
specified resource with the affected account, and remove those shares that you might
no longer require. You can also request an increase for a limit that supports
adjusting. Use the Service Quotas
console
Note
Amazon RAM doesn't automatically detect limit increase changes. You must re-associate the resource or principal to the resource share for RAM to detect the change.