Access is Denied is usually an indication of a permission issue or a configuration issue with the server. Instructions for WINDOWS:
1. Rollback 2. Ensure the user has full access for Clarity folder and to create a folder (i.e. if Clarity is in C:\Clarity, you need full access for C:\ as well 3. Ensure you always open the command prompt as Run as Administrator 4. Sometimes this also happens when permissions are very tight on this server , we recommend loosening them up 5. Reboot the server 6. Restart the upgrade and it should go through