NoSubitemsColumnInThisBoard - Error when creating subitems via the API

Hi there,
We are currently building an application which is able to create Boards, Groups, Items and SubItems via the API by importing third-party projects into monday.com (data formats which are currently not supported by the official importer).

Everything worked so far until we reached the SubItems. Attempting to create a SubItem via the create_subitem mutation results in a NoSubitemsColumnInThisBoard error telling that “There is no subitem column on this board, please add it first”.

Unfortunately creating SubItems is a key-feature for our use-case since we are importing data which is structured as multiple layers. Quick Example:

1.1 Collection of tasks
1.1.1 Main Task
1.1.1.1 Sub Task 1
1.1.1.1 Sub Task 2

We even tried to issue a create_column mutation with the undocumented type subtasks as observed in the UI which failed as well.

Is there any to create SubItems via the API without touching the Board in the UI? Thanks in advance!

For reference, this appears to be the same issue:

Hello @ilja and welcome to the community!

I hope you like it here :muscle:

As of today the only way of doing this is by creating a subitem in your board using the UI and then creating the subitems via API.

I will add your vote to the request of the feature for creating a subitem column via API :slightly_smiling_face:

Cheers,
Matias