When activating the dev mode (org.nuxeo.dev=true), the automation module is not activated properly, hence automation calls fail with following error (for instance when selecting groups when creating a user in the admin center):
java.lang.NullPointerException at org.nuxeo.ecm.automation.server.jaxrs.AutomationModule.setupSingletons(AutomationModule.java:53) at org.nuxeo.ecm.automation.server.jaxrs.AutomationModule.getSingletons(AutomationModule.java:77) at org.nuxeo.ecm.webengine.jaxrs.ApplicationFragment.getSingletons(ApplicationFragment.java:112) at org.nuxeo.ecm.webengine.jaxrs.ApplicationHost.getSingletons(ApplicationHost.java:195) at com.sun.jersey.api.core.ApplicationAdapter.<init>(ApplicationAdapter.java:56) at org.nuxeo.ecm.webengine.jaxrs.servlet.ApplicationServlet.init(ApplicationServlet.java:85) at org.nuxeo.ecm.webengine.app.jersey.WebEngineServlet.init(WebEngineServlet.java:38) at org.apache.catalina.core.StandardWrapper.initServlet(StandardWrapper.java:1280) at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1193) at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:865) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:136) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1023) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589) at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) at java.lang.Thread.run(Thread.java:724)
Problem was already visible with NXP-12404, so it seems it's not been fixed correctly.
Also when that happens for some reason, the cause of the issue should be more explicit, if possible.