I am using Mitaka and trying to update the stack using heat. But it gives me some error.

My stack for deployment -

heat_template_version: 2015-10-15

resources:

  Largeflavor:
    type: OS::Nova::Flavor
    properties:
      disk: 10
      ram: 1024
      vcpus: 2

  Management:
    type: OS::Neutron::Net
    properties:
      name: Management

  Management_subnet:
    type: OS::Neutron::Subnet
    properties:
      cidr: 10.0.0.0/24
      ip_version: 4
      name: Management_subnet
      network_id:
        get_resource: Management

  colocated:
    type: OS::Nova::Server
    properties:
      networks:
        - network:
            get_resource: Management
          port:
            get_resource: colocated_Management_port
      name: colocated
      image: MyImg
      flavor:
        get_resource: Largeflavor
      personality:
        /root/a.txt:
          get_file: "a.txt"

  colocated_Management_port:
    type: OS::Neutron::Port
    properties:
      network_id:
        get_resource: Management

And for the updation, by mistake I removed the personality line. My yaml file for updation is -

heat_template_version: 2015-10-15

resources:

  Largeflavor:
    type: OS::Nova::Flavor
    properties:
      disk: 10
      ram: 1024
      vcpus: 2

  Testflavor:
    type: OS::Nova::Flavor
    properties:
      disk: 10
      ram: 1024
      vcpus: 2

  Management:
    type: OS::Neutron::Net
    properties:
      name: Management

  Management_subnet:
    type: OS::Neutron::Subnet
    properties:
      cidr: 10.0.0.0/24
      ip_version: 4
      name: Management_subnet
      network_id:
        get_resource: Management

  colocated:
    type: OS::Nova::Server
    properties:
      networks:
        - network:
            get_resource: Management
          port:
            get_resource: colocated_Management_port
      name: colocated
      image: MyImg
      flavor:
        get_resource: Largeflavor

  colocated_Management_port:
    type: OS::Neutron::Port
    properties:
      network_id:
        get_resource: Management

The update procedure failed and the stack-show shows reason as -

No Flavor matching {'name': u'Largeflavor'}.

Is removing personality option allowed? If no, why this error? Shouldn't the error mention about personality?