InstallShield Error -1603 When Upgrading SmarterMail

While installing SmarterMail, an error may appear with an error code of -1603. This article explains how to troubleshoot the problem even if rebooting and attempting to reinstall the software does not succeed.
To resolve this issue, perform the steps found in this article from Solvusoft: How To Fix Installshield Error 1603
If this fails to resolve the problem, follow these steps:
  1. Uninstall SmarterMail if it shows up in your Add/Remove Programs.
  2. Using RegEdit, navigate to the key HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products
  3. Click on each GUID in tree under Products until you see one that has a ProductName value of SmarterMail. Right-click on the GUID and export the key as a backup, then delete the GUID from the tree and the subkeys beneath it.
  4. Run the SmarterMail installer.
  5. You may be required to reboot.
NOTE: Editing the registry can be a dangerous thing to do if you do not know what you are doing. Before attempting any changes to the Windows Registry, make a full backup of the registry and be sure you are familiar with the process.