Remove member and transfer files (409) Conflict

Please print out the HTTPS response body for the failing API call. It should contain a more specific error indicating what the issue is.

It doesn't look like it gets that far. This is an exception that happens at the point of invoking POST method and server returns: The remote server returned an error: (409) Conflict. The exception itself has Response property and it at it provides only the following:

IsMutuallyAuthenticated : False
Cookies : {}
Headers : {Transfer-Encoding, Connection, Content-Security-Policy, X-Dropbox-Request-Id...}
SupportsHeaders : True
ContentLength : -1
ContentEncoding :
ContentType : application/json
CharacterSet :
Server : nginx
LastModified : 26/03/2020 20:58:11
StatusCode : Conflict
StatusDescription : Conflict
ProtocolVersion : 1.1
ResponseUri : https://api.dropboxapi.com/2/team/members/remove
Method : POST
IsFromCache : False

This exception only happens if I have the transfer_dest_id in request body. If I remove it, the same request works OK, but without file transfer of course.

It doesn't look like it gets that far. The error is an exception that happens at the point of invoking the POST method and server returns: The remote server returned an error: (409) Conflict. The exception itself has Response property but it only provides the following:
IsMutuallyAuthenticated : False
Cookies : {}
Headers : {Transfer-Encoding, Connection, Content-Security-Policy, X-Dropbox-Request-Id...}
SupportsHeaders : True
ContentLength : -1
ContentEncoding :
ContentType : application/json
CharacterSet :
Server : nginx
LastModified : 26/03/2020 20:58:11
StatusCode : Conflict
StatusDescription : Conflict
ProtocolVersion : 1.1
ResponseUri : https://api.dropboxapi.com/2/team/members/remove
Method : POST
IsFromCache : False

This exception only happens if I have the transfer_dest_id in request body. Here is what I'm doing to execute the API call:
I'm using Powershell Invoke-RestMethod cmdlet as below. The headers only include Authorization
Invoke-RestMethod -Uri "https://api.dropboxapi.com/2/team/members/remove" -Method 'POST' -ContentType "application/json" -Headers $_headers -Body <one of the two examples below>

Examples of request bodies for endpoint: /members/remove

API call fails with this body:
{"user": {".tag": "team_member_id","team_member_id": "<team_member_id>"},"wipe_data": false,"transfer_dest_id": {".tag": "team_member_id","team_member_id": "<team_member_id>"},"keep_account": false,"retain_team_shares": false}

API call successful - user is disabled:
{"user": {".tag": "team_member_id","team_member_id": "<team_member_id>"},"wipe_data": false,"keep_account": false,"retain_team_shares": false}

Interestingly, if I just disable a user via /members/remove and then try to use /members/move_former_member_files to transfer files I'm also receiving exactly the same (409) Conflict response. I guess I must be doing something incorrectly.

This is the clue I was looking for. Thank you very much! The Stack Overflow article allowed me to see the response, as you mentioned, although it wasn't the approved solution that helped me. In the end the actual problem, that generated the 409 Conflict exception, was related to the fact that when doing file transfer the request has to include admin id as well (error_summary: unspecified_transfer_admin_id). An example request body looks like this:

"{"user": {".tag": "team_member_id","team_member_id": "<team_member_id>"},"wipe_data": true,"transfer_dest_id": {".tag": "team_member_id","team_member_id": "<team_member_id>"},"transfer_admin_id": {".tag": "team_member_id","team_member_id": "<team_member_id>"},"keep_account": false,"retain_team_shares": false}"

Bit of a schoolboy error - need to read documentation more carefully.

In any case the problem is solved so thank you for your help!