Resolving Eclipse’s “No Repository Found” Error

I have encountered a recurring problem with Eclipse 3.4. When performing an update of application components it fails during the download, and in the error it details “No Repository Found” for one or more (frequently a large number) of eclipse update site URLs.

I originally found the workaround solution several months ago, in the Eclipse bug tracker, and each time recurs I have to find it again (yes - a bookmark would be useful!) but, as it does not seem to be indexed by Google, each time it takes a lot of searching to (re)locate it. Hence I reference it here, primarily for my own benefit:

The solution is to be found in a comment by Lari Hotari to the ‘Lost Artifact Repositories’ bug 236437:

Here's a workaround:
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
4) Start eclipse
5) Import the bookmarks.xml file (Software Updates->Manage sites->Import)
    that was exported in step 1

Note: This has worked every time that I have encountered the problem, but I have seem other causes of the error, including an issue with HTTP proxies.

Additionally, I noticed another issue last night, that, after applying the fix to a rogue Ganymede installation, the AJDT Tools continued to fail with the same error. Comparing the update site list with a working system I found that the update URL that worked ended in a trailing ‘/’, unlike that of the failing system.

Removing the problem update site and adding it back in, this time with the trailing slash, fixed the issue, but whether that was due was the addition of the slash or merely the act of removing/replacing the entry, I don’t know.