If you get this error it probably means you have too many function arguments, local variables or return values in your function.

Instead of declaring 6 local variables it declares a single local variable that is a struct holding the 6 variables. Here’s a snippet:

struct SlotInfo {
  uint originalSelectorSlotsLength;
  bytes32 selectorSlot;
  uint oldSelectorSlotsIndex;
  uint oldSelectorSlotIndex;
  bytes32 oldSelectorSlot;
  bool newSlot;
// Using the struct to avoid Stack too deep error
function diamondCut(bytes[] memory _diamondCut) public override {
  SlotInfo memory slot;
  slot.originalSelectorSlotsLength = $selectorSlotsLength; 
  ... code omitted 
  if(selectorSlotLength > 0) {
    slot.selectorSlot = $selectorSlots[selectorSlotsLength];
  ... code omitted for simplicity