Just an FYI that I am experiencing the exact same error as Brian on a deployment (and I'm also the author of GAM).
We have however found a workaround for the issue. If you open the group's settings in a web browser, then API calls start succeeding for that group. So for example, if I'm getting the 503 Backend Error for
myg...@example.com then I can open Chrome and go to:
and from then on, GAM commands that update the group settings will succeed. However this is not scalable as opening a bunch of groups one right aftere the other in a browser will get you blocked by Google's automated process detection.
If any Googlers are looking into this, I've also filed ticket 02032230 with support on this issue.
Jay