"Could not load file or assembly" when installing or upgrading SmarterMail

During an initial installation, or an upgrade of older version of SmarterMail to the latest builds, sometimes the following error is encountered:
Server Error in '/' Application.
Could not load file or assembly 'SmarterMail.Data' or one of its dependencies. An attempt was made to load a program with an incorrect format.
What this means is that the server is attempting to run SmarterMail as a 32-bit application. SmarterMail builds that were released as of December 2018, versus SmarterMail 16.x builds and earlier, require 64-bit status. To resolve this issue, do the following:
  1. Log into the server.
  2. Open the Internet Information Services (IIS) Manager.
  3. Expand the server to expose Application Pools and Sites.
  4. Click on Application Pools.
  5. Right click on the SmarterMail application pool and select Set Application Pool Defaults.
  6. When the modal window opens, scroll to the top, if it's not already there.
  7. Find the General settings area.
  8. Make sure the Enable 32-Bit Applications line reads "False" -- if it says True, set it to False.
  9. Click OK and save your settings. 

Once you've done this, you should be able to hit the SmarterMail login page and log in normally and activate your license or do whatever is necessary.