Symptom
When attempting to use the Global ID as a the Update/Delete Key Field with the Esri Geodatabase (ArcSDE Geodb) writer, an error occurs:
An unsupported Esri field type was encountered. The Geodatabase Reader/Writer does not know to which Geodatabase field type to map this Esri field type
Cause
Global ID is a special ID that is used specifically for ESRI database replication. Creating a field with this datatype is not currently supported by FME. You can only create a feature class with a Global ID column by using the Esri Add Global ID tool after the feature class has been created.
You can write to an existing table with a Global ID column and similar to ObjectId, the Global ID field will be automatically populated with unique values. However, writing existing values does not work.
For more information about this Field type see: Geodatabase Field Data Types
Resolution
As of FME 2019.0, you can now preserve ESRI GlobalID fields when writing to ESRI Geodatabases. For more information, or to provide your feedback please see this Ideas Forum post: ESRI Global IDs.
In terms of maintaining GlobalID values when writing to an ESRI Geodatabase, no progress has been made due to the way GlobalIDs are handled. If you are writing an existing GlobalID to a new Geodatabase(with the same GlobalID data type), the Geodatabase automatically populates the GlobalID on INSERT. We are still unable to Update or Delete based on a GlobalID but we are hoping to add that in the future.
As a workaround, you may be able to write your existing GlobalID to a GUID field.
GlobalIDs are now supported as of FME 2019.0. Please see this Ideas post for the latest updates: https://knowledge.safe.com/idea/61583/esri-global-ids.html
