 <p>The issue mostly has to do with stale cached data (I experienced the same). The following should solve your problem.</p> <ol> <li>Go to: 'Preferences > Available Software Sites'</li> <li>Mark all, and 'Export' to file.</li> <li>Delete everything (all the links)</li> <li>Close and Start STS</li> <li>Go to: 'Preferences > Available Software Sites'</li> <li>'Import' from the previously saved file.</li> <li>Go to, 'Help > Check for updates'</li> <li>Update</li> </ol> <p>Basically this procedure clears up all the stale data.</p>