UEFN AddModifier Position Removed: Fix Verse Modifier Stack Order

UEFN AddModifier position removed is the change behind some Verse errors after Fortnite 43.10. AddModifier no longer accepts a position argument. Remove it, then add the modifiers in the order they need to run. Epic also removed FirstPosition, LastPosition and rational stack positions. The modifier system remains experimental, and islands using it cannot be published.

This affects modifier stacks behind experimental Scene Graph cameras and the Damage Pipeline. A script that used to place a modifier at an explicit position can now fail to compile or behave differently after migration. Do not treat the error as a random UEFN crash: it is a documented change in how the stack is assembled.

Why UEFN AddModifier position removed matters

A modifier stack takes a sequence of behaviours and applies them in order. Under the new system the sequence comes from when each modifier is added, not from a separately supplied rational position. That is easy to understand but important in practice.

Moving a camera before pointing it at a target is not necessarily equivalent to pointing first and then applying a movement offset. Likewise, a damage adjustment may produce a different result when it runs before or after another adjustment.

Fix Verse calls after UEFN AddModifier position removed

If you’re seeing the UEFN AddModifier position removed error, open the script that builds the stack and find calls that still supply a position. Make a note of the old execution order, remove the obsolete argument and add each modifier in that order. Check for FirstPosition and LastPosition references as well.

Some older API reference pages still show the previous signature, so check Epic’s November 12 release notes and your installed UEFN SDK before changing more code.

Test camera order after UEFN AddModifier position removed

Test the change in a private UEFN project with two or three Epic-provided camera modifiers. Add an attachment modifier, then a framing or collision modifier. Run the camera and swap their order to see the difference. For responsive camera movement, stick to Epic-provided modifiers: custom Evaluate code can make the entire stack run on the server.

UEFN AddModifier position removed: damage Pipeline stacks deserve the same check

The 43.10 change is not exclusive to cameras. Epic says the same modifier-stack update applies to the Damage Pipeline API. If your experimental setup changes incoming damage, healing or other results in a chain, compare the before-and-after output with fixed test inputs.

Even when the code compiles after removing the argument, a different order can change the final result. Do not assume the first successful build proves the migration is complete.

Do not treat an experimental prototype as publishable

Although the UEFN AddModifier position removed change is documented, Epic says the modifier stack system remains experimental and subject to change. The camera features using it are also experimental, so this migration is for UEFN experiments, not a guaranteed safe change to a published island.

Keep versioned backups, document the intended order and avoid claiming that any particular Verse snippet is compile-ready without running it against the current SDK.

Why an older example still shows Position

If you’re following an older camera-modifier tutorial, its AddModifier example may still accept a rational Position. Epic’s v43.10 release notes removed that argument, while some individual API reference pages still display the older signature. That mismatch can make the updated code look wrong when you compare documents side by side. Use the release notes for the change and your installed SDK for the current signature.

When migrating a stack, preserve its previous execution order before deleting Position values. If the old code inserted a modifier at the start or middle, you may need to rebuild the stack in the intended order instead of simply removing the argument from each call. Check the camera’s result or damage calculations, then retest after every edit.

UEFN AddModifier position removed FAQ

What happened to the AddModifier position argument? It was removed in v43.10. Modifiers now execute in the order they were added.

Do FirstPosition and LastPosition still work? No. Epic removed the rational positions and both helpers.

Is the modifier stack publishable? Not when it uses the experimental Camera or Damage Pipeline features covered by this change.

Official source: Epic Games documentation.