After extending the Active Directory Schema and adding custom attributes you may receive an error code 17 when launching a task in Identity Manager.
12.5 & 12.6
If you have created a new attribute on your user directory, your Identity Manager environment usually recognizes it. In rare cases it does not, you will want to make sure you take the following steps.
1. Make sure these steps were followed thoroughly:
2. Make sure your attributes are mapped properly in provisioning manager.
3. Make sure the user has proper permissions to add that custom attribute.
4. The directory schema may not have been updated on the corporate store router that is located on Application server.