Unable to Assign the 'Closed' Option on Salesforce Case Status Picklist Values

This article explains how to resolve the issue where the 'Closed' option cannot be assigned to a Salesforce Case Status picklist value. The root cause is that the active Support Process in the organization does not include a 'Closed' status value. Once 'Closed' is added to the Support Process and the 'Show Closed Statuses in Case Status Field' setting is enabled in Support Settings, the picklist value will be available.

Steps to Resolve in Salesforce Classic

1. Go to Setup | Customize | Cases | Support Processes.
2. Click your Support Process Name.
3. Add 'Closed' from Available Values to the Selected Values.
4. Click Save.

Steps to Resolve in Lightning Experience

1. Go to Gear icon | Setup | Feature Settings | Service | Support Processes.
2. Click your Support Process Name.
3. Add 'Closed' from Available Values to the Selected Values.
4. Click Save.

In Support Settings, ensure the "Show Closed Statuses in Case Status Field" is checked. The closed picklist values for the Case Status field will only be visible once this checkbox is checked.