Updating Sitecore can be a nightmare if you do not take the time to properly plan your update. First at all, you have to be sure about the current Sitecore version that you have and the version that you want to upgrade to. For this, just have to go to the Sitecore Login page and check the info in the right column.
Second, go to Sitecore’s SDN (Sitecore Developer Network) and navigate to the new version. For example, if you want to update from Sitecore.NET 6.5.0 (rev. 110602) to 7.0 rev.140408 (7.0 Service Pack-1), you’d follow this path: SDN à Products à Sitecore CMS à Sitecore 7 à CMS+DMS Downloads/Updates à 7.0 rev.140408 (7.0 Service Pack-1)
To upgrade from Sitecore 6.5 to Sitecore 7.0 you have to check the prerequisites:
Sitecore 7.0 requires at least Sitecore 6.6 rev. 120918, so you would have to execute the upgrade process twice (do the Sitecore 6.5 to Sitecore 6.6 upgrade first and then upgrade to Sitecore 7.0).
Lucene upgrade and related modules
Sitecore 6.5 uses Lucene.NET 126.96.36.199, but Sitecore 6.6 or greater uses a new version of Lucene, 2.9.4. This can cause many issues in the upgrade process because some modules use Lucene like Indexviewer or Weblog. In addition, there could be custom code that uses Lucene. To handle this, you’d have to uninstall these modules first (How to uninstall a Sitecore Package) and remove or comment all the code that refers to Lucene. Then run the update package. Then you would re-install the modules with the new versions available. If you don’t do this, the UpdateInstallationWizard will not let you update your Sitecore version (error shown below):
Upgrading your Sitecore version is a great way to ensure you can take advantage of Sitecore’s latest features as well as help keep your site secure; however, if you do not take the proper steps before your upgrade, you’ll end up wasting time and resources trying to update your site.
For more on how to update your Sitecore site, check out Part 2 of this series.