3830259 - Message: "This field is already used as a reference attribute." when trying to create a custom field referencing another field

• You are trying to create a custom reference attribute field by referencing the field to another field on different entity but the field is grayed out and cannot be added
• Message: "This field is already used as a reference attribute." is displayed instead.

SAP Sales Cloud and SAP Service Cloud Version 2

1. The KBA is valid for any entity. For illustration purpose, we will consider example of field creation within Case entity referencing to field defaultExternalBusinessPartnerId from Accounts
2. Click on System Profile
3. Go to System Settings
4. Go to Extensibility Administration
5. Go to the case entity
6. Create new field 
7. Select Data Type: String and Data Format: Token
8. Enable the Custom Reference Attribute toggle
9. Click on Add Custom Reference Attribute
10. Open the fields under Owner/Account
11. See the field defaultExternalBusinessPartnerId is grayed out and the message "This field is already used as a reference attribute." is displayed

By design, few fields such as defaultExternalBusinessPartnerId are enabled for direct use in the entity, and therefore cannot be referenced by another custom field.

1. This is the expected system behavior.
2. You can directly use these fields on UI or in Custom logic of the particular entity without having to reference it in another custom field in order to use it

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