Spring ’26 (API Version 66.0)

Require Visible No-Argument Constructors for Apex Classes

Custom Apex classes used as invocable action parameters now require an accessible no-argument constructor. These classes typically contain properties annotated with @InvocableVariable. This requirement applies when flows, REST API, or Apex code call invocable actions.

If your custom Apex class defines other constructors, add an explicit no-argument constructor. Use a public access modifier for classes in your org or within the same package. Use a global access modifier for classes in managed packages to make them accessible from subscriber orgs.

If a flow references an Apex invocable action with a parameter defined in an Apex class, the system checks for an accessible no-argument constructor. If the Apex class lacks an accessible no-argument constructor, Flow Builder shows an error when you configure that action's inputs.

Record-Triggered Flows Issue with Non-Insertable Fields Was Fixed

Record-triggered flows that run before records are saved now respect the internal writeable status of non-insertable fields. If existing flows try to update fields that aren’t editable, this error message appears: Invalid target field for field update.