This can happen if the "person_type" attribute is null in the odf_default_overrides table. One reason this can happen is due to perform the below steps:
Go to Administration->Objects->Resource
Enter a default value for Person Type and Save
Delete the default value entered in Person Type and Save
Resolution
Step 1: Run the below query to verify there is a null value for 'person_type':
Select * from odf_default_overrides where object_code='resource' and attribute_code='person_type';
If the results return with a blank value for 'person_type', proceed to Step 2
Step 2: Create backup of odf_default_overrides table
Step 3: Run below query:
delete from odf_default_overrides where object_code='resource' and attribute_code='person_type' and value is NULL; Commit;
Step 4: Flush PPM cache (or restart app services)
Steps to flush PPM cache:
a. Login to the Clarity PPM application as an admin user b. Modify the URL field to: http://<svr>/niku/nu#action:security.caches c. Click Caches tab, click FLUSH ALL button