Error with references

Hello forum, I am a big noob (just starting today :D) at UE4 getting started with Blueprints.

I was using the Starter Map to tinker with some lights. My particular goal was to create a couple of lights which can be toggled on and off by pressing a key, but only if a nearby general light switch (that you can also toggle on and off) is toggled on.
I created the general light switch in the level blueprint, and the two lights are implemented via a class blueprint.

In order to know if I can turn those two lights on and off, my class blueprint needs to know if the general switch is on or off, so I created a variable (in the class blueprint) of object type to reference the level blueprint and be able to get a boolean variable from there. The thing is, when I add the variable which references the level blueprint, I cannot save until I delete it because I get the following error message:

Error1.PNG

And when I press OK…

Error2.PNG

I have tried looking for a solution everywhere I could think of, but I have found none thus far. I apologize for asking if this is somehow an easily solved issue.

I normally get the first message when I had a round about reference set up and then went to save the blueprint.

Check to see who is referencing who and see if you can adjust it so they are not referring to each other in a circle which may be causing the issue. Level -> light and then the light -> level which causes the level -> light and repeat.

Sorry for late answer. I did not find any circular references but I found out that the level blueprint does not (yet?) support referencing nor the use of interfaces. I am looking into event dispatchers but still haven’t managed :(. Thanks for answer!

Wow I feel like such an idiot. My doubt was resolved in this tutorial:- YouTube
Gonna go hide in a corner now :D.