Can somebody help me to understand where is the problem?
I am trying to build level 6 that is in index as number 5. Levels 1-5 work without errors.
“Blueprint Runtime Error: Attempted to access index 5 from array B_BestTime of length 5! from function: ‘ExecuteUbergraph_SideScrollerCharacter’ from node: Set BestTimeText in graph: EventGraph in object: SideScrollerCharacter with description: Attempted to access index 5 from array B_BestTime of length 5!”
Here is a picture of the BP.
Maybe the item of index 6 does not exist.
“Attempted to access index 5 from array B_BestTime of length 5” to me says that the array contains elements with indices [0, 1, 2, 3, 4] (i.e., five elements). Hence, accessing index 5 has to fail…
However, your screenshot shows on the left that the default of the array has 10 entries… Maybe you could have a PrintString-Node that shows you the length of the array right before you access it with your routine, to make sure that all elements are still present?
I would guess that somewhere the number of elements is modified…
EDIT: On the very left of your screenshot the BestTime is set from a target we cannot see. Are you sure that at this point you still have all elements present? You are taking that array out from a particular object? I guess we need some more information here 
I found out the problem. I only needed to delete the savegame file and everything works.