SYMPTOM:
When updating schema in Strategy Developer, below error appears:

Error(s) occurred while loading schema: [DFCSCHEMA] Population Exception: The object shown in the following hierarchy no longer exists in schema: -Link-Attribute:(unexpected) Table GUID: 26DA70D04EE87D3C8916B383FBFE613F.

ACTION:
The issue is resolved by removing the blank expression through attribute editor.
Starting from 11.0, we enhanced the error message so the attribute which causing the issue will be printed out. The error message in 11.0 looks below:
Error(s) occurred while loading schema: [DFCSCHEMA] Population Exception: The object shown in the following hierarchy no longer exists in schema: -Link-Attribute:(unexpected) Attribute name: Delivery Qtr. Table GUID: 26DA70D04EE87D3C8916B383FBFE613F.