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Re: [jetty-users] ProxyServlet$Transparent returns 502 for external sites
  • From: "Houtman, Roland" <Roland.Houtman@xxxxxxxxxxxxxxx>
  • Date: Fri, 19 Jul 2019 08:44:14 +0000
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  • Thread-topic: [jetty-users] ProxyServlet$Transparent returns 502 for external sites

I also tried;


1 ### Let Jetty use PROXY settings

using the next flags for the VM in order to let Jetty use our company proxy






               It still gave the 502/Bad gateway


2 ### Changing the proxy to refer to https directly

( Because if I navigate to the http url (as written in the original web.xml) with my browser it redirects to the https variant. So I thought maybe the servlet doesn’t cope with the redirct. )



To refer to

Instead of http://,  Now when I access the demo-base  Javadoc link then, I get this:


Problem accessing /proxy/current/. Reason:

    Server Error

Caused by:

java.lang.NullPointerException: Missing SslContextFactory

  at java.util.Objects.requireNonNull(


  at org.eclipse.jetty.client.HttpClient.newSslClientConnectionFactory(

  at org.eclipse.jetty.client.HttpDestination.newSslClientConnectionFactory(

  at org.eclipse.jetty.client.HttpDestination.<init>(

  at org.eclipse.jetty.client.PoolingHttpDestination.<init>(

  at org.eclipse.jetty.client.http.HttpDestinationOverHTTP.<init>(

  at org.eclipse.jetty.client.http.HttpClientTransportOverHTTP.newHttpDestination(

  at org.eclipse.jetty.client.HttpClient.destinationFor(

  at org.eclipse.jetty.client.HttpClient.send(

  at org.eclipse.jetty.client.HttpRequest.send(

  at org.eclipse.jetty.client.HttpRequest.send(

  at org.eclipse.jetty.proxy.AbstractProxyServlet.sendProxyRequest(

  at org.eclipse.jetty.proxy.ProxyServlet.service(







From: jetty-users-bounces@xxxxxxxxxxx <jetty-users-bounces@xxxxxxxxxxx> On Behalf Of Houtman, Roland
Sent: Friday, July 19, 2019 9:43 AM
To: JETTY user mailing list <jetty-users@xxxxxxxxxxx>
Subject: Re: [jetty-users] ProxyServlet$Transparent returns 502 for external sites




I downloaded Jetty latest 9.4, ran the demo-base and was looking around,

Then I found that the transparent-proxy is used for redirecting to the online Javadoc



So, I click it and I also get “502 bad gateway”


Is there some logging which I can pick up to see why the remote site returns 502?



Kind regards



From: jetty-users-bounces@xxxxxxxxxxx <jetty-users-bounces@xxxxxxxxxxx> On Behalf Of Joakim Erdfelt
Sent: Thursday, July 18, 2019 7:29 PM
To: JETTY user mailing list <jetty-users@xxxxxxxxxxx>
Subject: Re: [jetty-users] ProxyServlet$Transparent returns 502 for external sites


Start by upgrading your version of Jetty, and try again.


Version 9.0 was an experimental / transitional release series between Servlet 3.0 (Jetty 8) and 3.1 (Jetty 9).

That series has been EOL (End of Life) for a long time. (many years now)


Joakim Erdfelt / joakim@xxxxxxxxxxx



On Thu, Jul 18, 2019 at 11:50 AM Houtman, Roland <Roland.Houtman@xxxxxxxxxxxxxxx> wrote:



I’m trying to use the ProxyServlet$Transparent

So far I am succeeding when proxying HTTP requests to my local GeoServer


But when I proxy to a www URL, then I get 502 bad gateway on two separate servers.


I’m working from office, so I do work behind a proxy.

What are things I can check to come closer to fixing this issue?


I listed the test URLS in the web.xml for reference and minimal-test-setup

Using jetty-9.0.7.v20131107


Kind regards,







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