HttpError 400 when requesting groups settings

Question

I'm getting an error executing previosly-working code. Getting groups settings fails with this:

<HttpError 400 when requesting https://www.googleapis.com/groups/v1/groups/<group email>?alt=json returned "A system error has occurred"> () {'status': '400', 'alternate-protocol': '443:quic', 'x-xss-protection': '1; mode=block', 'x-content-type-options': 'nosniff', 'transfer-encoding': 'chunked', 'expires': 'Wed, 09 Oct 2013 08:36:59 GMT', 'server': 'GSE', 'cache-control': 'private, max-age=0', 'date': 'Wed, 09 Oct 2013 08:36:59 GMT', 'x-frame-options': 'SAMEORIGIN', 'content-type': 'application/json; charset=UTF-8'

{
 "error": {
  "errors": [
   {
    "domain": "global",
    "reason": "invalid",
    "message": "A system error has occurred"
   }
  ],
  "code": 400,
  "message": "A system error has occurred"
 }
}

Moreover, API explorer fails too, with a different error message: 400 Bad Request.
Field groupUniqueId is filled with an existing group in the domain and I'm a domain admininstrator.

Can you try the API Explorer to confirm this error?

Answer 1

Update: as of moments ago the problem appears to be resolved.

Answer 2

I can confirm there is a problem with GET, I tried working code and API explorer and multiple domains.