I'm wondering if the subnet you're using is in a VPC that is in the legacy EC2-Classic and not EC2-VPC mode.
If your VPC is not in legacy EC2-Classic, are you using a default or non-default VPC?
Also note when using Application Migration Service, the EC2 launch template does not automatically set a specific Subnet. Thus, if not specified, it will try to launch in a subnet as part of that default VPC. If the default VPC is removed, EC2 will fail to launch any instance if there's no valid subnet specified.
I configured the specific network subnet in EC2 launch template settings and solved the issue.
EC2 linux instance migrated using Application Migration Service (ASM) does not initialize correctly Networkasked 2 months ago
Is there a programmatic way to download the EC2 Instance Recommendations from Migration Hub?asked 5 months ago
MGN Converter Instance Start and Stop in less than two minutesasked 4 months ago
Failing to launch test/cutover instance with public IPasked 9 months ago
migrated using the application migration service instance can't startasked 7 months ago
Migration using same IP address and hostnameasked 3 months ago
Application migration service installerasked 2 months ago
Can't launch instance - Server.InternalError: Internal error on launchasked 4 years ago
Application Migration Service With Key Pairasked 19 days ago
Restoring an EC2 Instance - the Public IP is missingAccepted Answerasked 3 months ago