Accepted answer

What version of eclipse are you using ?

It has been fixed in 3.4.1, but in your case, it could be this bug instead.

It turns out the cause is one or more artifact repositories being lost from the list of known repositories.

The workaround is to remove the repository from the list and add it back again. This restores the missing artifact repository.

A possible workaround in eclipse 3.4.1:

  1. export the update site listing to bookmarks.xml file (Software Updates->Manage sites->Export)
  2. stop eclipse
  3. remove configuration/.settings/org.eclipse.equinox.p2.*.prefs files
    (Note, as mentioned by Fredrik in the comments, for Eclipse3.5+, this would be:
  4. start eclipse
  5. import the bookmarks.xml file (Software Updates->Manage sites->Import) that was exported in step 1

As mentioned by mark (author of this question) in the comments of this answer, that workaround was a solution for his problem.

Other advice:

[...] the solution is always to append a trailing '/' to all repository URLs in my P2 UI.
My feeling is that this error is caused by a failure to construct a viable URL to a repo resource. The code in question is not inspecting the URL string from the UI and is assuming a trailing '/' resulting in a 404

This last solution is confirmed working in Eclipse Indigo and Juno (below in the comments).


I had the same problem. After exporting and importing bookmarks, the problem did not get resolved. but I started getting error 'Connection refused'.

On further thoughts I found that my antivirus is not allowing eclipse to talk to internet. Disabling antivirus made it work.

Sandeep Jindal


I had a similar problem over the last couple months, but ignored it until I really needed PyDev to work on my laptop today.

I tried the solutions above to no avail and then I found something odd:

In (Window->Preferences->Install/Update->Available Software) I noticed that the box for 'PyDev Update Site' AND another one right below it with the location 'file:/updates' were both checked, causing a duplicate of most or all update URLs. After un-checking the box with the location 'file:/updates' I was able to update from (Help->Check for Updates) which then successfully installed the latest version of PyDev.

This solution might not be applicable to PyDev updates alone and could hopefully help others with similar issues.


I just had the same problem, I diabled my ZoneAlarm Firewall, and it connected OK!

Is there some kind of rule I need to add into my firewall to stop it blocking eclipse? It never used to do this, everything was working find until last week (Sept 25th (ish) 2012)


When I encountered a similar problem I add the following repository to my available update site.

Make sure the slash in at the end of the URL.


There is a simple solution for this problem, that I tested, on, just install "Eclipse Tests, Examples, and Extras" -> "Eclipse 2.0 Style Plugin Support" from The Eclipse Project Updates repository


In my case the problem was caused by having two update sites for STS of which one one obsolote and not available any more. Both were present and checked in Install/Available Software Sites.

Solution was simple: unchecking the site that was not available. Available update sites for sts are listed here:


I had the same problem (well similar as I was just trying to install subclipse). VonC's tip "Other advice" did it for me.

  1. Export sites to bookmarks.xml
  2. Edit this file and append a forward slash at the end of every URL where it is missing.
  3. Delete all sites
  4. Re-import edited bookmarks.xml
  5. Sigh with relief as it works.


The backslash thing in the exported bookmarks file fixed it for me.


I had the same problem with Eclipse Helios (3.6) on Ubuntu 64 bits.


from the "Available Software Sites" in Eclipse, and adding it again did the fix.


Though this question is answered a long back, wanted to share my experience thinking that it may save some one' day :)

Some times it could also be possible due to the incorrect proxy settings. In my case (Eclipse 3.6/Helios), Eclipse preference file $ECLIPSE_HOME$/configuration/.settings/ is having proxy details,


When I deleted the file after closing the Eclipse, then onwards I m able to download the plugins


Yet another solution -

Instead exporting all managed sites and importing them back, click on 'edit' on each checked site and add '//' at the end

If you just add a '/' it says duplicate site therefore the '//'

How a small bug in a huge carefully architected application can be so hard to debug yet simple to solve

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