Creating tenant through API returns response 500 on successfully created tenant

Response from curl:

<?xml version="1.0" encoding="UTF-8"?>
<hash>
<status>500</status>
<error>Internal Server Error</error>
</hash>

Logs from system-app:

[7c0fa776-ca35-4f3c-ba2b-8529a665846b] [master-admin.3scale.cloudapps.api-qe.eng.rdu2.redhat.com] [10.128.2.1] Completed 201 Created in 1158ms (Views: 0.4ms | ActiveRecord: 530.9ms)
Exception – [7c0fa776-ca35-4f3c-ba2b-8529a665846b] [master-admin.3scale.cloudapps.api-qe.eng.rdu2.redhat.com] [10.128.2.1] undefined method `empty?' for #<Signup::ResultWithAccessToken:0x000000088d5a60>
[7c0fa776-ca35-4f3c-ba2b-8529a665846b] [master-admin.3scale.cloudapps.api-qe.eng.rdu2.redhat.com] [10.128.2.1]
NoMethodError (undefined method `empty?' for #<Signup::ResultWithAccessToken:0x000000088d5a60>):
lib/action_dispatch/rails5_ssl.rb:86:in `call'
10.40.3.183 - - [28/Feb/2018:08:38:48 +0000] "POST /500 HTTP/1.1" 500 116 1.1769