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Asked: 2025-05-05T16:14:38+05:30

How can I prevent objects from appearing as Missing when switching back to a previously loaded scene in Unity?

I’m working on a tool in Unity that needs to store and retrieve certain objects from the currently active scene. As part of my system, I’m using ScriptableSingleton to save object IDs, which is working pretty well. I retrieve them when the scene changes, which is mostly smooth sailing. However, I’ve run into a situation that’s a bit of a headache.

Here’s the deal: when I switch scenes, my tool is notified if it’s currently open, and it loads the necessary objects without issue. The problem crops up when I try to streamline the process. I thought it’d be a good idea to set a bool flag for scene changes when the tool isn’t open, to avoid unnecessary retrievals. So, when the tool isn’t open and I switch back to the last scene where the object data was loaded, my logic prevents reloading those objects. It seems like a good optimization, but that’s where things get wonky.

When I switch back to the scene, all the objects that should be there appear as “Missing.” It’s super frustrating because they exist in the scene, but I can’t interact with them as expected. I used to have this problem sorted out because my retrieval method fired off every time the tool opened. Now, though, it’s like Unity can’t recognize the objects because my optimization led to them not reloading.

One thing that’s baffling me is whether I can find a way to ensure that the objects are recognized without having to hit the retrieval function again. I initially thought about using some kind of scene reload listener or perhaps a different approach to check the state of the objects. But I want to avoid redundant operations, as performance is key for this tool.

Has anyone run into something similar, or does anyone have any ideas on how to bypass this “Missing” issue when attempting to prevent unnecessary reloads? Would it make sense to keep a temporary cache of the objects when a scene loads? Any insights or creative solutions would be super appreciated!

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    2 Answers

    1. It sounds like you’re dealing with a tricky situation! From what you’ve described, it seems like your optimization is causing Unity to not recognize the objects when switching scenes, which leads to them showing as “Missing”. That’s definitely frustrating!

      One thing you might want to try is caching the references to the objects manually when the scene loads. Instead of relying solely on the retrieval function, you could create a simple dictionary or list to store the IDs of the objects along with their references when the scene is loaded. That way, even if the tool isn’t open, you still have access to the references. When the scene is loaded again, you could check this cache before trying to reload the objects.

      Another idea is to listen for scene change events directly in your tool. You could use Unity’s SceneManager to subscribe to scene load events. This way, no matter if the tool is open or not, you could check if the relevant objects are already loaded or not and handle them accordingly. It could help keep things in sync without unnecessary retrievals.

      Also, consider setting up a system where you can validate if the objects are still valid when you switch back to the scene. Maybe you could use a simple check to see if those objects exist in the scene before trying to access them. This could prevent you from running into the “Missing” issue, as it’ll ensure the references are correct and help you maintain performance.

      Good luck! I hope you find a solution that works for your tool!

    2. It appears your current optimization approach inadvertently skips a needed step when the tool isn’t active, causing Unity’s serialized object references to lose context and appear as “Missing.” Unity relies on instance IDs that might change between scene reloads, so saving only object IDs without reestablishing references upon scene switches can result in invalid references. Using a temporary caching mechanism, such as storing weak references or maintaining a dictionary mapping unique identifiers to GameObjects upon each scene load, could help preserve valid references without incurring significant overhead.

      Additionally, consider employing Unity’s scene event methods like SceneManager.sceneLoaded or editor-specific callbacks such as EditorSceneManager.sceneOpened, which reliably trigger upon each scene change. These events could be leveraged to conditionally re-establish your object references efficiently. By selectively invalidating and recreating caches only on scene transition events rather than continuously reloading, you can maintain correct references with minimal performance cost, effectively eliminating the “Missing” object scenario while maintaining your optimization goals.