REST - Update project description (412) Precondition Failed

[mctavi]

Update project description not working from updateproject.ps1 for project created with createproject.ps1 - code:
$body = "{'Description':'Updated from PowerShell using REST API'}"
Patch-ReSTRequest $SiteUrl "ProjectServer/Projects('$projectid')/Draft" $body

Exception calling "GetResponse" with "0" argument(s): "The remote server returned an error: (412) Precondition Failed."
At C:\vault\ps\ReST.ps1:126 char:5

• $resp = $request.GetResponse()
  

• ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  

  • CategoryInfo : NotSpecified: (:) [], MethodInvocationException
  • FullyQualifiedErrorId : WebException