How to Fix the Stack Overflow Error When Disabling Unity Input Action Maps

Discover why disabling input action maps in Unity causes stack overflow errors and learn how to fix it with an updated input system.
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Disabling a Unity input action map in its own callback causes an error

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding the Stack Overflow Error in Unity's New Input System

As game developers, we often encounter unique challenges when working with different systems and frameworks. One such problem arises when using the new Unity Input System, specifically when attempting to disable an input action map within its own callback. If you've stumbled upon this issue, you're not alone. This guide dives into the root of the problem while providing a solution that will help you get back to developing your game seamlessly.

The Problem

When you try to disable an input action map inside one of its callbacks in Unity, you may encounter a daunting error message: StackOverflowException. This error occurs due to an unintended infinite loop created by the mechanics of the callback system. For example, the issue can appear in a scenario like the following:

Sample Code

[[See Video to Reveal this Text or Code Snippet]]

In this code, triggering Up_IAMOne() disables IAM_One and tries to enable IAM_Two, which successfully calls Up_IAMTwo() and starts the process over, leading to a loop of continuous callbacks.

The Solution

Fortunately, the Unity development team has addressed this issue. The solution is straightforward: update your Unity Input System to version 1.1.0-preview.1 or higher. This version is available for Unity 2019.4.0f1 and above and includes fixes for the aforementioned problematic behavior.

Steps to Update the Input System

Open Unity Hub: Initiate your Unity Hub and select the project you wish to update.

Access the Package Manager: Click on Window in the top menu, then navigate to Package Manager.

Locate the Input System: In the Package Manager, find the Input System in the list of installed packages.

Update: If an update is available, you will see an option to update alongside the version number. Click on it to install the latest version.

Test Your Code: After the update, rerun your code. The stack overflow error should now be resolved, allowing you to re-enable and disable your action maps without issue.

Conclusion

In conclusion, while encountering a StackOverflowException can be frustrating, knowing that the root cause is tied to how the callback system in Unity's new input framework is implemented empowers developers to resolve it. By keeping your tools updated, you can prevent these issues and continue focusing on creating engaging and interactive gameplay. Update your Unity Input System today and enjoy the newfound stability in your input handling logic!