SonarQube 5.3 log: "Undefined method 'empty?' for nil:NilClass" error messages
<p>Why do I get this error message?</p>

<pre><code>[o.s.s.ui.JRubyFacade] Fail to render: ....
undefined method 'empty?' for nil:NilClass
/web/WEB-INF/lib/authenticated_system.rb:132 in 'login_from_basic_auth'
org/jruby/RubyProc.java:290 in 'call'
org/jruby/RubyProc.java:224 in 'call'
...
</code></pre>

<p>We have seen this error during rendering of different SonarQube "pages": /sessions/login and /api/qualityprofiles/export?language=cs&amp;name=....&amp;exportKey=resharper.cs and we could not reproduce this on an other environment. Looking in old postings we found several Ruby related hits on 'undefined method empty' but not connected with SonarQube.</p>