REST API: create project with powershell returns unspecified internal error

Question

I'm creating a a project with the code below.
The response is always an unspecified error.

Invoke-RestMethod : {"$id":"1","innerException":null,"message":"TF400898: An Internal Error Occurred. Activity Id: 3fbed4b2-9751-41ba-acbe-4d20f02ae556.","typeName":"System.Web.Http.HttpResponseException, System.Web.Http","typeKey":"HttpResponseException","errorCode":0,"eventId":0}
At line:1 char:1
Invoke-RestMethod -Uri $adoTaskUri -ContentType "application/json-pat ...
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
CategoryInfo : InvalidOperation: (System.Net.HttpWebRequest:HttpWebRequest) [Invoke-RestMethod], WebException
FullyQualifiedErrorId : WebCmdletWebResponseException,Microsoft.PowerShell.Commands.InvokeRestMethodCommand

I tried the body in postman and the projects are created just fine.

Can someone see what I'm doing wrong?
Listing of the projects works; the body works in postman; I can create tasks with a similar script.

$pacToken = ""
$organizationName = "BLECUST"

$adoHeader = @{"Accept"="application/json";Authorization=("Basic {0}" -f [Convert]::ToBase64String([Text.Encoding]::ASCII.GetBytes(("{0}:{1}" -f "",$pacToken))))}
#$adoHeader #accept about anything and add security in the header

#api to create 
$adoTaskUri = "https://dev.azure.com/BLECUST/_apis/projects?api-version=5.1"


#list all projects
$response = Invoke-RestMethod -Uri $adoTaskUri -ContentType "application/json-patch+json"  -headers $adoHeader -Method GET
$response.value | ft name, visibility, url

$body='{
  "name": "FabrikamTravel18",
  "description": "Frabrikam travel app for Windows Phone",
  "capabilities": {
    "versioncontrol": {
      "sourceControlType": "Git"
    },
    "processTemplate": {
      "templateTypeId": "6b724908-ef14-45cf-84f8-768b5384da45"
    }
  }
}'


Invoke-RestMethod -Uri $adoTaskUri -ContentType "application/json-patch+json" -Body $body-headers $adoHeader -Method POST

Answer 1

Your script works, just update the last content type to application/json:

Invoke-RestMethod -Uri $adoTaskUri -ContentType "application/json" -Body $body -headers $adoHeader -Method POST

PATCH is used to update a team project: https://docs.microsoft.com/en-us/rest/api/azure/devops/core/projects/update?view=azure-devops-rest-6.1