I need to configure Jenkins to send notification on our Slack channel #builds.
I configured the Jenkins CI integration in Slack. As a result, I have a token "abcdefgh666", and when I expand the "Setup instructions", I can see our team domain is "mysuperteam". We connect to slack with the url <http://mysuperteam.slack.com>

I am stuck on step 3. On [Slack doc](https://github.com/jenkinsci/slack-plugin), the screenshot is the following:

[![slack screen](https://i.stack.imgur.com/pCl8U.png)](https://i.stack.imgur.com/pCl8U.png)

But in our Jenkins version, the view looks like:

[![my screen](https://i.stack.imgur.com/u82OX.png)](https://i.stack.imgur.com/u82OX.png)

Obviously, the Test Connection button always return a Failure. In Jenkins logs, I have this many times:

```
Mar 30, 2017 2:14:38 PM WARNING jenkins.plugins.slack.StandardSlackService publish
Error posting to Slack
java.lang.IllegalStateException: Target host is null
    at org.apache.http.util.Asserts.notNull(Asserts.java:46)
    at org.apache.http.impl.client.InternalHttpClient.determineRoute(InternalHttpClient.java:125)
    at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:185)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:82)
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:106)
    at jenkins.plugins.slack.StandardSlackService.publish(StandardSlackService.java:126)
    at jenkins.plugins.slack.SlackNotifier$DescriptorImpl.doTestConnection(SlackNotifier.java:510)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.kohsuke.stapler.Function$InstanceFunction.invoke(Function.java:335)
    at org.kohsuke.stapler.Function.bindAndInvoke(Function.java:175)
    at org.kohsuke.stapler.Function.bindAndInvokeAndServeResponse(Function.java:108)
    at org.kohsuke.stapler.MetaClass$1.doDispatch(MetaClass.java:124)
    at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:58)
    at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:746)
    at org.kohsuke.stapler.Stapler.invoke(Stapler.java:876)
    at org.kohsuke.stapler.MetaClass$5.doDispatch(MetaClass.java:236)
    at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:58)
    at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:746)
    at org.kohsuke.stapler.Stapler.invoke(Stapler.java:876)
    at org.kohsuke.stapler.MetaClass$5.doDispatch(MetaClass.java:236)
    at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:58)
    at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:746)
    at org.kohsuke.stapler.Stapler.invoke(Stapler.java:876)
    at org.kohsuke.stapler.Stapler.invoke(Stapler.java:649)
    at org.kohsuke.stapler.Stapler.service(Stapler.java:238)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
    at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:812)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1669)
    at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:135)
    at hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:126)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652)
    at hudson.security.csrf.CrumbFilter.doFilter(CrumbFilter.java:80)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652)
    at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:84)
    at hudson.security.UnwrapSecurityExceptionFilter.doFilter(UnwrapSecurityExceptionFilter.java:51)
    at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
    at jenkins.security.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:117)
    at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
    at org.acegisecurity.providers.anonymous.AnonymousProcessingFilter.doFilter(AnonymousProcessingFilter.java:125)
    at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
    at org.acegisecurity.ui.rememberme.RememberMeProcessingFilter.doFilter(RememberMeProcessingFilter.java:142)
    at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
    at org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:271)
    at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
    at jenkins.security.BasicHeaderProcessor.doFilter(BasicHeaderProcessor.java:93)
    at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
    at org.acegisecurity.context.HttpSessionContextIntegrationFilter.doFilter(HttpSessionContextIntegrationFilter.java:249)
    at hudson.security.HttpSessionContextIntegrationFilter2.doFilter(HttpSessionContextIntegrationFilter2.java:67)
    at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:87)
    at hudson.security.ChainedServletFilter.doFilter(ChainedServletFilter.java:76)
    at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:171)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652)
    at org.kohsuke.stapler.compression.CompressionFilter.doFilter(CompressionFilter.java:49)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652)
    at hudson.util.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:82)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652)
    at org.kohsuke.stapler.DiagnosticThreadNameFilter.doFilter(DiagnosticThreadNameFilter.java:30)
    at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1652)
    at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:585)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
    at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:553)
    at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:223)
    at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1127)
    at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:515)
    at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:185)
    at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1061)
    at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
    at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:97)
    at org.eclipse.jetty.server.Server.handle(Server.java:499)
    at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:311)
    at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:257)
    at org.eclipse.jetty.io.AbstractConnection$2.run(AbstractConnection.java:544)
    at winstone.BoundedExecutorService$1.run(BoundedExecutorService.java:77)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)

```

I tried using the credentials menu to avoid putting the token directly, I tried to put "slack.com" in "Base URL" field, I tried to check or uncheck the "Is Bot User ?" field, and I tried to put "<http://mysuperteam.slack.com>" in "Base URL" field.

Is my configuration correct ? What could prevent Jenkins to connect to Slack ?