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Looks like this is an AWS restriction. You’ll presumably need a name other than

sg

in your code above. From https://docs.aws.amazon.com/vpc/latest/userguide/VPC_SecurityGroups.html: Names and descriptions can be up to 255 characters in length. Names and descriptions are limited to the following characters: a-z, A-Z, 0-9, spaces, and ._-:/()#,@[]+=&;{}!$*. A security group name cannot start with sg-. A security group name must be unique within the VPC.

Thanks, that solved the problem.