1.5 changed the Role API format, introducing 'filters' for roles, rather than straight permissions.

In 1.4.2, curl -s -u admin:changeme -k -H "Content-type:application/json" https://localhost/api/roles returned

{ "name": "Manager", "id": 1, "builtin": 0, "permissions": [ "view_architectures", "create_architecture",<snip>

In 1.5.0, curl -s -u admin:changeme -k -H "Content-type:application/json" https://localhost/api/roles returns

{"error":{"message":"undefined method `key?' for #<JSON::Ext::Generator::State:0x00000009afb938>"}}

The production.log stack trace is attached.

If I change the API version to 2, curl -s -u admin:changeme -k -H "Content-type:application/json" https://localhost/api/v2/roles
The response is
{ "total": 12, "subtotal": 12, "page": 1, "per_page": 20, "search": null, "sort": { "by": null, "order": null }, "results": [{"name":"Manager","id":1,"builtin":0},{"name":"Edit partition tables","id":2,"builtin":0},{"name":"View hosts","id":3,"builtin":0},{"name":"Edit hosts","id":4,"builtin":0},{"name":"Viewer","id":5,"builtin":0},{"name":"Site manager","id":6,"builtin":0},{"name":"Default user","id":7,"builtin":1},{"name":"Anonymous","id":8,"builtin":2},{"name":"Anonymous_admin","id":15,"builtin":0}] }
Which responds with a group of filters instead of actual permissions, as the API documentation suggests.

Lastly, running the command curl -s -u admin:changeme -k -H "Content-type:application/json" -X POST -d @test.json https://localhost/api/v2/roles, where test.json contains
{ "role": { "permissions": [ "view_environments", "view_facts", "view_hostgroups", "view_hosts", "edit_hosts" ], "name": "tester" } }
gives the error message

{
  "error": {"message":"Permission(#72168980) expected, got String(#15746520)"}
}