[SalesForce] Case Milestone related list

You can not update TargetDate and most of the other fields on CaseMilestone as these are not writable fields.

According to the SOAP API Developer Guide, the only fields which allow update are Start Date and Complete Date.

Salesforce doesn't close the previous active milestone automatically when you are changing the case status and creates a new milestone.

With the help of apex you need to search the active milestone (e.g.Milestone 1) of the Case and update the completion date in the CaseMilestone record.

Refer the below screenshot for understanding.

Please find the related code to complete the milestone. Refer Case Milestones Utility Class

public static void completeMilestone(List<Id> caseIds, String milestoneName, DateTime complDate) {

    List<CaseMilestone> cmsToUpdate = [select Id, completionDate
                       from CaseMilestone cm
                       where caseId in :caseIds and cm.MilestoneType.Name=:milestoneName and completionDate = null limit 1];
    if (cmsToUpdate.isEmpty() == false){
      for (CaseMilestone cm : cmsToUpdate){
        cm.completionDate = complDate;
      }
      update cmsToUpdate;
    } // end if
  }