With this update, event log files are generated and delivered only to orgs that opt in to receive event log files. Previously, all orgs received event log files automatically. This update automatically disables event log file generation for Developer and Trial editions and for orgs that don’t have the Event Monitoring add-on subscription by default. If you have Salesforce Shield or Salesforce Event Monitoring add-on subscriptions, you’re opted in to receiving event log files by default. This update was first available it Spring ’23 and is enforced in Summer ’23.
Where: This change applies to Lightning Experience and Salesforce Classic in Enterprise, Performance, Unlimited, and Developer Editions.
When: This update was first available in Spring ’23 and is enforced in Summer ’23. To get the major release upgrade date for your instance, go to Trust Status, search for your instance, and click the maintenance tab.
How: To review this update, from Setup, in the Quick Find box, enter Event Monitoring, and then select Event Monitoring Settings. Turn on or off Generate event log files.
Opt in for Event Log File Generation (Release Update) (salesforce.com)