Prefab being destroyed on client connection for unknown reason

Asset & Content Management
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I’m finding it increasingly challenging to pinpoint the precise cause of why my network prefab is vanishing when a client initiates a connection.

Here’s a brief overview of the components in question:

1. NetworkUI (prefab): This prefab incorporates a ‘DontDestroyOnLoad’ function and contains the NetworkManagerUI (script) .
2. NetworkManager (prefab): This prefab maintains a reference to NetworkUI (prefab) .

Our NetworkUI (prefab) houses the user interface needed for establishing server connections or its own operation as a server. It’s designed to be a persistent component, hence it’s embedded into the network prefab list managed by NetworkManager (prefab) .

To ascertain if NetworkUI (prefab) is encountering an unexpected destruction, I added an OnDestroy() event listener into the NetworkManagerUI (script) . The logs point to the ‘connect button’ as the culprit.

Upon firing the client connection method, it hits the breakpoint and without delay, the destruction command is called immediately upon exiting.

Despite exploring all configuration options related to network objects and even creating a fresh Unity project, the issue persists.

Surprisingly, NetworkUI (prefab) isn’t destroyed on the server’s end. It seems when initiating a client connection, an attempt is made to spawn a clone of NetworkUI (prefab) for the client. Yet, it falters as it can’t locate it in the NetworkPrefabs list. Output: ([Netcode] Failed to create object locally. [globalObjectIdHash=2371489523]. NetworkPrefab could not be found. Is the prefab registered with NetworkManager?)

In essence, I’m dealing with a perplexing problem - the unexplained disappearance of my network prefab during client connection. Despite rigorous troubleshooting, this error remains unresolved .

2

Now go find out why! Network code has to be debugged too.

Time to start debugging! Here is how you can begin your exciting new debugging adventures:

You must find a way to get the information you need in order to reason about what the problem is.

Once you understand what the problem is, you may begin to reason about a solution to the problem.

What is often happening in these cases is one of the following:

  • the code you think is executing is not actually executing at all
  • the code is executing far EARLIER or LATER than you think
  • the code is executing far LESS OFTEN than you think
  • the code is executing far MORE OFTEN than you think
  • the code is executing on another GameObject than you think it is
  • you’re getting an error or warning and you haven’t noticed it in the console window

To help gain more insight into your problem, I recommend liberally sprinkling Debug.Log() statements through your code to display information in realtime.

Doing this should help you answer these types of questions:

  • is this code even running? which parts are running? how often does it run? what order does it run in?
  • what are the names of the GameObjects or Components involved?
  • what are the values of the variables involved? Are they initialized? Are the values reasonable?
  • are you meeting ALL the requirements to receive callbacks such as triggers / colliders (review the documentation)

Knowing this information will help you reason about the behavior you are seeing.

You can also supply a second argument to Debug.Log() and when you click the message, it will highlight the object in scene, such as Debug.Log("Problem!",this);

If your problem would benefit from in-scene or in-game visualization, Debug.DrawRay() or Debug.DrawLine() can help you visualize things like rays (used in raycasting) or distances.

You can also call Debug.Break() to pause the Editor when certain interesting pieces of code run, and then study the scene manually, looking for all the parts, where they are, what scripts are on them, etc.

You can also call GameObject.CreatePrimitive() to emplace debug-marker-ish objects in the scene at runtime.

You could also just display various important quantities in UI Text elements to watch them change as you play the game.

Visit Google for how to see console output from builds. If you are running a mobile device you can also view the console output. Google for how on your particular mobile target, such as this answer for iOS: https://discussions.unity.com/t/700551 or this answer for Android: https://discussions.unity.com/t/699654

If you are working in VR, it might be useful to make your on onscreen log output, or integrate one from the asset store, so you can see what is happening as you operate your software.

Another useful approach is to temporarily strip out everything besides what is necessary to prove your issue. This can simplify and isolate compounding effects of other items in your scene or prefab.

Here’s an example of putting in a laser-focused Debug.Log() and how that can save you a TON of time wallowing around speculating what might be going wrong:

https://discussions.unity.com/t/839300/3

“When in doubt, print it out!™” - Kurt Dekker (and many others)

Note: the print() function is an alias for Debug.Log() provided by the MonoBehaviour class.