On occasion when high enough concurrent allocate machine API calls (using github.com/juju/gomaasapi) hits the region controller, the controller responds on some with Error 409: Conflict Error.
```
Error: <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>Error: Conflict Error</title>
</head>
<body>
<h2>
Conflict error. Try your request again, as it will most likely succeed.
</h2>
</body>
</html>
```
Simply re-running the batch of API calls resumes allocating the ones that didn't allocate previously.
If instead the controller would return an error of 503: Service Unavailable, the gomaasapi has built-in retry logic.
A 409 means that a conflict has occurred. MAAS internally retries 10 times to try and handle conflicts with IP allocation when allocating a machine with AUTO IP addresses. If you are getting failures in this case then the its now the clients turn to retry the action.
This is a bug in the gomaasapi for not retrying the action.