Can't create DMS Instance with The Replication Subnet Group already exists

Hi

I just had the same problem when creating a new replication instance in AWS console. First time I hit the create button I had another error, I fixed it, hit create button again and then I had the same error 'Subnet Group already exists'.

I went to the 'Subnet groups' page (in DMS) and manually deleted the existing subnet group. Then the creation went just fine.

Seems like the subnet group creation is not rolled back when an error occurs.

Maso's solution worked for me too.