When attempting to load one or more lists or libraries, Sharegate displays the following error:
Feature '00000000-0000-0000-0000-000000000000' for list template '12345' is not installed in this farm. The operation could not be completed.
This error happens because a list or library was created in your SharePoint site based on a given list template that is no longer available.
A common scenario for this type of error is a list that was created with a template defined by a feature that has since been uninstalled. This makes the list invalid because the template no longer exists. When Sharegate sends a request to SharePoint to load this list or library, SharePoint returns an error because it cannot find the list template.
Re-install the feature in your SharePoint farm to make the list template available again. This will allow SharePoint to return it correctly when Sharegate tries to load it.
Alternatively, if the list giving the error is a list that is no longer used, deleting the list will prevent this error.