Why do I see a 404 error when trying to upload to an eDocBuilder template using the InDesign plugin?

If you are seeing a 404 error when trying to upload an eDocBuilder template using the InDesign plugin, it means that the Preferences > eDocBuilder > Server setting is incorrect in InDesign.
 
If the Server setting is blank and you did enter a value for that setting before restarting InDesign, it can be an indication that your preferences file for the plugin is not being saved. See points 9, 10 & 11 on the article Ch. 036 InDesign Plug-in for eDocBuilder.
 
If the Sever setting has a value that begins with creator, like creator.edocbuilder.com, then it needs to be changed to the correct server address value. See point 8 on the article Ch. 036 InDesign Plug-in for eDocBuilder.