This error occurs when you are navigating in your Explorer or selecting a target for a report (if this error occurs when running a report, it will display in the report results page). When you attempt to drill down to your subsite, you are brought back up to your parent site. Sharegate will display this error message:

The queried site {site name} is not responding. This can indicate an issue with your alternate access mapping configuration. Please review your configuration before retrying the operation.

As indicated, this error usually means there is an issue with your alternate access mappings configuration. Alternate access mappings is how SharePoint is able to connect and query the URLs associated to the environment. You can read our Connection Issues and Alternate Access Mappings blog to understand more on this.

Due to an issue in the configuration, Sharegate cannot query the information needed, and when you try to drill down to the subsite, you will be redirected back up to the parent site. If there was no error, and you were able to keep retrying the action, you would be caught in an infinite loop.

You will need to verify your alternate access mappings configuration. Alternatively, you can disconnect from your environment and try to connect again using your internal URL.