Why do I see "Error describing Salesforce table. Please try again." when logged into the Soapbox administrator?

Problem:

As a site administrator logged in to the backend, I see a large set of error messages on login "Error describing Salesforce table. Please try again."

Cause:

This error message means that Soapbox isn't able to talk to Salesforce's API, which most likely is due to a problem with the login credentials set in the System - J!Salesforce Libraries Plugin such as a Salesforce password or security token that was reset but not updated.

Solution:

Login to your Soapbox administrator and go to Extensions > Plugin Manager. Search for the plugin called "System - J!Salesforce Libraries" and open it to edit. Update the username, password and token fields accordingly. The error message should disappear as soon as the credentials are correctly updated.