Symptoms
If you attempt to install the Server extension on a computer that does not have a SharePoint Web Front End (WFE) installed on it, this message will be displayed:
Error 1001. SharePoint was not found on this server. The Sharegate Extension must be installed on your SharePoint farm's front-end servers.
Solution
The Server Extension must be installed on all SharePoint WFE servers. If multiple Front Ends are available via Load balancing, you must install the extension on each front end.
Follow the Server Extension Checklist to help ensure the installation goes well.