Error when trying to create a Group and User in the same Template

Hello, I had that idea too but it seems as the DependsOn key is not permitted when creating a user, i got the following error the first time i tried it:

Properties validation failed for resource USRENAME with message: #: extraneous key [DependsOn] is not permitted.

So for your example it would be:

Properties validation failed for resource hogehoge with message: #: extraneous key [DependsOn] is not permitted.

No, you can use "DependsOn". We are seeing successful deployments using the template below. The error you shared can occur if the yaml is mis-indented.

AWSTemplateFormatVersion: 2010-09-09
Description: test.

Resources:
  Group:
    Type: "AWS::IAM::Group"
    Properties:
      GroupName: "custom"
      Path: "/"
      ManagedPolicyArns:
        - "arn:aws:iam::aws:policy/AmazonS3FullAccess"

  UserHogehoge:
    DependsOn: Group
    Type: "AWS::IAM::User"
    Properties:
      Path: "/"
      UserName: "hogehoge"
      Groups:
        - !Ref Group

I'm using json format:

"Parameters": {
"UserPass" : {
            "Type": "String",
            "Description": "Users initial password",
            "Default": "blahblah123"
        },
"TestGroupName" : {
            "Type": "String",
            "Description": "TEST Group Name",
            "Default": "AWS-TEST"
        }
    },

"Resources": {
"GroupTEST":{
            "Type" : "AWS::IAM::Group",
            "Properties" : {
                "GroupName" : {"Ref":"TestGroupName"},
                "ManagedPolicyArns" : [
                   "arn:aws:iam::aws:policy/AmazonS3FullAccess"
                    ],
                "Path" : "/"
            }
        },
"UserHogehoge" : {
            "Type": "AWS::IAM::User",
            "Properties": {
                "Groups": [  
                    {"Ref" : "TestGroupName"}
                ],
                "UserName": "hogehoge",
                "DependsOn": "GroupTEST",
                "LoginProfile": {
                    "Password" : {"Ref":"UserPass"},
                    "PasswordResetRequired" : "True"
                }
            }
        }

Does the position of the DependsOn key matter? I just saw that this template is using the FormatVersion 2010-09-09 also maybe that might be an issue?

The position of "DependsOn" is important. Please try as below.

"Parameters": {
"UserPass" : {
            "Type": "String",
            "Description": "Users initial password",
            "Default": "blahblah123"
        },
"TestGroupName" : {
            "Type": "String",
            "Description": "TEST Group Name",
            "Default": "AWS-TEST"
        }
    },

"Resources": {
"GroupTEST":{
            "Type" : "AWS::IAM::Group",
            "Properties" : {
                "GroupName" : {"Ref":"TestGroupName"},
                "ManagedPolicyArns" : [
                   "arn:aws:iam::aws:policy/AmazonS3FullAccess"
                    ],
                "Path" : "/"
            }
        },
"UserHogehoge" : {
            "DependsOn": "GroupTEST",
            "Type": "AWS::IAM::User",
            "Properties": {
                "Groups": [  
                    {"Ref" : "TestGroupName"}
                ],
                "UserName": "hogehoge",
                "LoginProfile": {
                    "Password" : {"Ref":"UserPass"},
                    "PasswordResetRequired" : "True"
                }
            }
        }

Good morning, I just tried it and i still get the same error that [DependsOn] is not permitted. :(

Update: I tried to create a new stack and it worked on there no error for DependsOn so I assume it might be some other issue with the one stack already in place?