How to publish a draft Task Group via Azure DevOps API - powershell

Question

I am in the process of converting some tasks inside numerous task groups we have to different tasks. Instead of doing this by hand I've opted for using Powershell along with the Rest API of Azure DevOps to update the JSON bodies of these task groups and send them to the API. The conversion of the tasks is working fine sofar.
sending a PUT to the rest API in order to update the current task group of the set works but I want to build in some retention / version history if some of the new tasks end up working different than expected. So just blatantly updating the existing Task Group under the same major version is not an option.
the UI of Azure DevOps has functionality where you can save changes to a task group as a 'draft' and then publish this draft as either a completely new version (major version + 1) or as a preview
I went ahead and attempted to send a PUT to the Rest API and upticking the major version using the following URI:
PUT https://dev.azure.com/{organization}/{project}/_apis/distributedtask/taskgroups/{taskGroupId}?api-version=5.1-preview.1
Along with the settings:
JSONObject.version.major = $currentversion + 1
JSONObject.preview = true
This results in the API returning an error saying:
Invoke-WebRequest : {"$id":"1","innerException":null,"message":"Task group {TaskGroupID} not found.","typeName":"Microsoft.TeamFoundation.DistributedTask.WebApi.MetaTaskDefinitionNotFoundException, Microsoft.TeamFoundation.DistributedTask.WebApi","type
Key":"MetaTaskDefinitionNotFoundException","errorCode":0,"eventId":3000}
I then went ahead and tried to see if I could create a draft version. When sending a POST to the following URI i was able to create a draft:
POST https://dev.azure.com/{organization}/{project}/_apis/distributedtask/taskgroups?api-version=5.1-preview.1
using the following settings in JSON:
JSONObject.version.major = 1
JSONObject.version.istest = true
JSONObject.id = $null
JSONObject.parentDefinitionId = {TaskGroupID of the taskgroup of which i am trying to make a draft}
This nets in a new Task group in draft state which i am able to view in the UI and modify and publish (with or without preview). When i export the created JSON from UI from a manually made draft and compare it versus the one coming from powershell i see no differences.
This last step is where I am stuck. I can't seem to convert the created draft into a new version of the {parentdefintionid} task group. I've tried the following settings:
Calling the taskgroupid URI of the parent with put while a draft is available
JSONObject.version.major = $currentversion + 1
JSONObject.version.isTest = false
JSONObject.preview = true
Removing ParentDefinitionID from JSONObject
is resulting in the same error where it states that it cannot find the ID of the parent:
Invoke-WebRequest : {"$id":"1","innerException":null,"message":"Task group {TaskGroupID} not found.","typeName":"Microsoft.TeamFoundation.DistributedTask.WebApi.MetaTaskDefinitionNotFoundException, Microsoft.TeamFoundation.DistributedTask.WebApi","type
Key":"MetaTaskDefinitionNotFoundException","errorCode":0,"eventId":3000}
The same is valid with above settings and calling the draftID URI
When i try to call the draftID task group URI with the following settings :
JSONObject.version.major = $currentversion + 1
JSONObject.version.isTest = false
JSONObject.preview = true
JSONObject.id = $ParentDefinitionID
Removing ParentDefinitionID from JSONObject
it results in the following error:
Invoke-WebRequest : {"$id":"1","innerException":null,"message":"The request specifies task group ID {parentTaskGroupID} but the supplied task group has ID {DraftTaskGroupID}.","typeName":"Microsoft.TeamFoundation.DistributedTask.WebApi.Task
GroupIdConflictException, Microsoft.TeamFoundation.DistributedTask.WebApi","typeKey":"TaskGroupIdConflictException","errorCode":0,"eventId":3000}
i've checked the actual JSONObject to an export of a published Task Group in UI and they match exactly so i'm quite positive that content is not the issue here.
The MS documentation is seriously lacking on API usage so i'm really in the dark there hoping to find some clues / solution here

Answer 1

Seems you were updating a already exist task group in Azure DevOps.
If you incremented the revision property to be 1 higher than what is currently deployed.
You need to submit the JSON with the same revision property that the server has.