Object reference variable is empty at runtime

Why: Your code reads from a '{ref}' reference, but nothing was assigned to it. UE5 doesn't error at compile time, but warns that the runtime access will crash with null-pointer. Fix: Wherever this BP spawns, set the reference via Spawn Actor From Class → Set Reference. If it should be set from outside, expose the variable (eye-icon = Instance Editable) so it's set in the level editor. Add an Is Valid? Branch before each read to gracefully handle null.

Cast To

Safely converts an Object Reference to a more specific class. Branch on the Failed output — casting to the wrong class returns null.

IsValid — check if object reference is valid (not null or pending kill)

IsValid is a MACRO with two exec outputs: 'Is Valid' and 'Is Not Valid'. NOT a pure bool function.

string

string

Function has a local variable that's never read

Why: You created a local variable '{var}' inside this function, but no node ever reads it after assignment. It's just dead code. Fix: Either: (a) delete the variable and the Set node that writes to it, or (b) add a Get '{var}' node and connect it to wherever you actually need the value (if this was an oversight).

Less (float) — A < B

Cast target class doesn't exist or was deleted

Why: Your Cast To node references the class '{class}' which has been removed or renamed since you added the cast. Fix: Click the Cast To node. In Details panel, click the dropdown next to 'Cast To Class' and re-select the actual current class. If the class is truly gone, replace this Cast with an Interface call or a different type test.

Calling a function that doesn't exist on the target object

Why: You're calling '{fn}' on an object that doesn't have that function. The function may have been deleted, renamed, or moved to a different class. UE5 can't bind the call at compile time. Fix: Check the target pin's type. Search the Content Browser for the actual class name + look for '{fn}' in its functions. If found, drag a fresh reference and use the proper context menu Call Function path. If gone, find a replacement function or use an Interface call.

GetDataTableRow asks for a row that doesn't exist

Why: Your code looks up '{row}' in a DataTable, but no row with that name is present in the DataTable asset. Fix: Open the DataTable asset in Content Browser. Check the row names in the Row Editor panel. Either: (a) add the missing '{row}' row manually, or (b) update the lookup to use an existing row name, or (c) wire a Get All Row Names → ForEachLoop instead of hardcoding the name.

Enhanced Input Action asset is missing

Why: A node references the InputAction '{ia}' which was deleted, renamed, or never created. The compiler can't bind to it. Fix: In Content Browser, search for '{ia}'. If found: re-link the node by dropping it on the workspace + replacing the broken reference. If missing: create the InputAction (Content Browser → right-click → Input → Input Action), then add it to your InputMappingContext.