UPDATE #3: There is the potential that after running Rollback-FIPFSEngine.ps1 that you may see the following error in the Application Event Logs: Log Name: Application Source: Microsoft-Filtering-FIPFS Date: 01/04/2022 00:00:00 Event ID: 6027 Task Category: None Level: Error Keywords: User: NETWORK SERVICE Computer: exchange-server.domain.com Description: MS Filtering Engine Update process was unsuccessful to download the … Continue reading Exchange FIP-FS Scan Engine Update Issues: How to roll-back the update