Upgrading from 1.5.20b to 1.5.21b
Before performing an update you should take your site offline by replacing the index.lc file with a static one.
Step 1: Update your revIgniter files
Replace these files in your "system/libraries" folder with the new versions:
Replace this file in your "system/revigniter" folder with the new version:
Step 2: Update your user guide
Please replace your local copy of the user guide with the new version.