Hi, Google is phasing out this type of plugin. In fact the Google Earth plugin won't work in Chrome now unless you re-enable plugins via a flag. You can read more about this here:
If you go to the GE plugin page (https://www.google.com/earth/explore/products/plugin.html
) in Chrome, unless you have enabled the flag (chrome://flags/#enable-npapi), you will be told you need to download the plugin. When you try to install it again, as you already have it, you will get the 1603 error.
As soon as you enable npapi and restart Chrome, you will see on the GE plugin page that the plugin is installed.
The GE plugin page needs updating with an explanation, and Google is aware of this, but whether they will do it is another matter ...
This page is specifically for the Tour Builder, but it's quite informative even if you are using a different product or site: