Eclipse help won't show under Ubuntu

Question

Whenever I open some help within eclipse I get a page saying:

Server Error. The following error occurred: [code=CANT_CONNECT_LOOPBACK] Cannot connect

Answer 1

David, thanks for the netstat output; you'll notice that Eclipse is listening on an IPv6 port:

Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name

tcp6 0 0 :::55934 :::* LISTEN 1956/eclipse

Is your proxy configuration set to bypass both 127.0.0.1 and ::1?

Answer 2

Eclipse help is actually an HTTP server.

This is probably a permissions problem with your installation of Eclipse.

I have no suggestions except to check the permissions on your Eclipse folder, or delete and reinstall Eclipse.

Answer 3

I know this is a late answer, but I had the same problem and resolved it, so to tie up this one...

This is a combination of two bugs:

(i) Eclipse's internal help browser doesn't use the Eclipse proxy settings! See: https://bugs.eclipse.org/bugs/show_bug.cgi?id=318969

(and the bugs referenced in comment #7 therein)

(ii) Ubuntu's proxy support is horribly broken in certain subtle ways. See: https://bugs.launchpad.net/ubuntu/+bug/300271

The fix/workaround is to manually set the no_proxy environment variable before running eclipse (as reported in the Eclipse #308035 bug referenced from the 318969 one) e.g.

export no_proxy=127.0.0.1,localhost
eclipse &

Help then launches correctly within Eclipse. Of course, once Eclipse is launched (thus running its own internal HTTP server), you can also access the local help manually from another browser (or, if within the 'can't access 127.0.0.1' screen, there's an icon at the top to launch in an external window --> default system browser).

This may well apply on other Linux distros using Gnome.

[Couldn't post the 308035 bug link because my low reputation means I can only post 2 hyperlinks :-( Getting excited at this privilege come 10 reputation points :-)]

Answer 4

Basically, this error means that Eclipse is failing to establish a TCP/IP connection to your localhost using 127.0.0.1 (Eclipse starts a server for the Help).

If you are using some specific proxy settings (either global at the OS level or local at the Eclipse level), double check that you are bypassing the proxy for localhost and 127.0.0.1.

If this doesn't help, try setting the hostname that help uses to localhost when starting eclipse (either on the command line or in the eclipse.ini):

eclipse -vmargs -Dserver_host=localhost

Answer 5

had the same problem recently installing and running Eclipse on 9.10. Found that the default settings for Eclipse were fine but 9.10 had no proxy bypass set for 127.0.0.1 in its system settings. Also had to install Apache2 via Synaptic. I installed Apache2, did not change any settings for Apache2 and then went System > Preferences > Network Proxy Preferences clicked on Ignored Hosts and added "127.0.0.1". Reset the Eclipse Network Preferences back to default, restarted Eclipse and help worked perfectly. Hope this works for others.

Answer 6

Make sure your /etc/hosts file is properly done. Usually

• if the line containing 127.0.0.1 has your host name remove it and just leave 'localhost'
• if the opposite were true, try adding your hostname to it :)

such things happen because gnome is trying to match hostname and sockets to handle UI things. Might be worth asking on superuser..