A content type hub is a site collection dedicated to creating and publishing content types to other site collections and web applications.
When you modify content types in your hub, your changes apply to all instances of these content types in other site collections in your environment.
Note: ShareGate Migrate does not fully support content type hubs.
Index
Migrating a content type hub
You can migrate the site collection you use as a content type hub.
However, ShareGate Migrate does not activate the features necessary for its proper function at the destination.
After you migrate a content type hub site collection, you will have to:
Activate the Content type syndication hub feature.
Create a Managed metadata service in the Manage metadata service application for your content type hub.
Note: It can take about 1 hour when you publish your content types. This is because the content types in your hub get copied to your other sites by the Content type hub and Content type subscriber timer jobs in SharePoint. While you can manually run these jobs in an on-premises SharePoint environment, you cannot do so in Microsoft 365.
Migrating content types that come from a content type hub
This applies to migrating site objects (sites, lists, content types, etc.) that use content types published by a content type hub at the source.
When a content type gets published from a content type hub, SharePoint copies it into the site collections in your environment. Its link to the content type hub is kept through a unique ID that ShareGate Migrate does not support. This means that:
When you migrate a content type from a content type hub, it is copied as a standard one.
If you migrate a content type with the same name as a destination content type from a content type hub, it will not get copied directly to the hub.
Migrating content types to a content type hub
While you can migrate content types from any site collection to a content type hub, you must publish them manually at the destination.
Content types of the same name are merged in the content type hub at the destination. When combined, you must publish the content type in the hub to apply the changes to all the subscriber site collections.
To learn how to publish content types, see Microsoft's article Publish a content type from a content publishing hub.
Migrating content types to a site collection that subscribes to a content type hub
In SharePoint on-premises versions
When you migrate a content type with the same name as a content type from a hub in your destination, the source content type is merged into its counterpart at the destination.
Because content types from a hub are read-only by default, ShareGate Migrate will likely skip migrating the content type's information.
You can remove the read-only constraint to copy the information from the source, and this will not detach the content type from the hub at the destination since it will preserve the destination's ID.
In Microsoft 365
Microsoft has changed how content type publishing works in Microsoft 365.
Instead of the content type hub pushing content types everywhere in your environment, users pull content types directly from the hub as they add them to lists and libraries in your environment.
Because of this new behavior, ShareGate Migrate cannot see a destination content type from a hub until it's used on a list or library.
This will cause ShareGate Migrate to copy a new content type of the same name with a different ID and source that will not be attached to the content type hub at the destination.
To circumvent this problem, you can manually provision your destination site collection at the destination, create a temporary library to add all the content types you require from the hub, and copy your source site into it to merge them.