An unknown error occupied while creating a group

[patricknasc]

After opening a session, I try to use it to create a group but it keeps returning the following error as response.

curl -X 'POST' \
  'http://localhost:3000/client/createGroup/ABCD' \
  -H 'accept: */*' \
  -H 'x-api-key: qwert!123' \
  -d ''
{"success":true,"response":"CreateGroupError: An unknown error occupied while creating a group"}%                                                                                                                   

By the way, how is the procedure to create a group with the api? First I create, then add participants and change the group properties, like name and so on? Is there a specific order to proceed to create a group successfuly?