Me helped the following solution:
- Go to Help->Software Updates, then select the Available Software tab and click the Manage Sites button
- Use the Export button to export the sites to a bookmarks.xml file
- Open the bookmarks.xml file in your favorite text editor, and add a trailing “/” to any of the site urls which are missing the “/” or remove on the end. Save the changes.
- Back in the Manage Sites window within Eclipse, select all of the sites and click the Remove button
- Now, click Import and load in the edited bookmarks.xml file
It was taken from this link Devon Hillard's Digital Sanctuary