If you do not have a "default" process engine (because multiple tenants are configured) cockpit does not start at all - because it tries to login via the default engine(see below).

–
java.lang.RuntimeException: java.lang.NullPointerException
org.camunda.bpm.webapp.impl.security.auth.AuthenticationFilter$1.execute(AuthenticationFilter.java:61)
org.camunda.bpm.webapp.impl.security.auth.AuthenticationFilter$1.execute(AuthenticationFilter.java:56)
org.camunda.bpm.webapp.impl.security.SecurityActions.runWithAuthentications(SecurityActions.java:38)
org.camunda.bpm.webapp.impl.security.auth.AuthenticationFilter.doFilter(AuthenticationFilter.java:56)

root cause

java.lang.NullPointerException
org.camunda.bpm.webapp.impl.engine.ProcessEnginesFilter.getDefaultEngineName(ProcessEnginesFilter.java:179)
org.camunda.bpm.webapp.impl.engine.ProcessEnginesFilter.serveIndexPage(ProcessEnginesFilter.java:97)
org.camunda.bpm.webapp.impl.engine.ProcessEnginesFilter.applyFilter(ProcessEnginesFilter.java:66)
org.camunda.bpm.webapp.impl.filter.AbstractTemplateFilter.doFilter(AbstractTemplateFilter.java:42)
org.camunda.bpm.webapp.impl.security.filter.SecurityFilter.doFilterSecure(SecurityFilter.java:67)
org.camunda.bpm.webapp.impl.security.filter.SecurityFilter.doFilter(SecurityFilter.java:51)
org.camunda.bpm.webapp.impl.security.auth.AuthenticationFilter$1.execute(AuthenticationFilter.java:59)
org.camunda.bpm.webapp.impl.security.auth.AuthenticationFilter$1.execute(AuthenticationFilter.java:56)
org.camunda.bpm.webapp.impl.security.SecurityActions.runWithAuthentications(SecurityActions.java:38)
org.camunda.bpm.webapp.impl.security.auth.AuthenticationFilter.doFilter(AuthenticationFilter.java:56)