Introduction
Unity is one of the most powerful game engines available today, but sometimes even simple Android builds run into unexpected errors. One common issue faced by Unity developers—especially beginners—is the build failure that shows the message:
“java.lang.UnsupportedOperationException: This feature requires ASM7. See the console for details.”
This error can be frustrating because it stops the APK build process completely, and Unity does not clearly explain the actual reason behind it. Most developers try changing JDK or reinstalling Unity, but the fix is much simpler.
In this detailed guide, I will explain why this error appears, how to easily fix it, and what settings you should double-check before building your APK. This solution works for all Unity Android projects, including games, simulations, and educational apps.
Let’s get started.
Summary of the Problem
While building an Android APK using Unity, the build process stops and throws the following error:
“java.lang.UnsupportedOperationException: This feature requires ASM7.”
This usually happens after clicking the Build button in Build Settings. Unity starts creating the APK, but halfway through, the build fails. Developers often think something is wrong with scripts, JDK, or modules—but the real issue is related to the Target API Level.
The error occurs because your selected API level is not compatible with the ASM version Unity is using. When the API level is too high for your current Unity version or build tools, Unity fails to process it and stops the build.
Good news: the fix is extremely simple—just lower your Target API Level.
Steps to Fix “ASM7 Build Failure” in Unity
Follow these steps exactly as described. This is the same process I demonstrated in the video, and it works 100% of the time.
Step 1: Close the Unity Editor Completely
If the build has failed:
- Save your project
- Close Unity Editor
- Wait a few seconds so Unity shuts down background processes
This step ensures Unity resets the temporary build files.
Step 2: Reopen the Same Project
Now re-launch Unity and open the exact project where you faced the problem.
This rebuilds the internal build cache that Unity uses for Android builds.
Step 3: Open Build Settings
Go to:
File → Build Settings
Select Android as the platform (if not already selected).
Then click:
Player Settings
Step 4: Go to Player Settings → Identification
In the Player Settings window:
- On the left panel, click Player
- Scroll down to Identification
- Find the option Target API Level
Here you will see something like:
- API Level 30
- API Level 33
- API Level 34
- Highest Installed
- or something similar
This is the setting causing the build error.
Step 5: Reduce the Target API Level
Now the actual fix:
● If your API level is 30, reduce it to 29
● If your API level is 29, reduce it to 28
● If your API level is 27, reduce it to 26
General rule: Reduce the Target API Level by 1 step.
Unity becomes compatible again, and the build works smoothly.
Step 6: Build the APK Again
Now:
- Go back to Build Settings
- Click Build
- Save the APK on your desktop (or any folder)
You will now see the APK building process start and finish successfully.
✔ The “ASM7 feature requires…” error disappears
✔ The APK builds without any failure
✔ No extra plugins, no reinstallation, no heavy fixes required
Final Result: Build Successful
After reducing the API level, Unity completes the APK build without any errors. The “java.lang.UnsupportedOperationException: This feature requires ASM7” issue is fixed permanently.
You can now:
- Export your game
- Install the APK on your Android device
- Upload it to Play Store (if needed)
- Continue building future versions easily
This method works for all versions of Unity that support Android builds.
❓ Frequently Asked Questions (FAQs)
1. Why does Unity show the ASM7 error during APK build?
Answer: Because the selected Target API Level is not compatible with the ASM version Unity is using. When Unity tries to process a higher API level that it does not fully support, it fails the build.
2. Will reducing the API level cause problems on new Android devices?
Answer: No. Most Android versions are backward compatible. API Level 29 and 28 still work smoothly on modern Android devices.
3. Should I reinstall Unity or Android SDK?
Answer: No. The problem has nothing to do with installation or missing SDK files. Only the API level mismatch causes this error.
4. Does this error affect game performance?
Answer: Not at all. It only affects the build process. Once the APK builds successfully, there is no impact on the game or app’s performance.
5. Can I publish an app with API Level 29 on Google Play Store?
Answer: If you are publishing to Play Store, Google requires a specific minimum API level (usually the latest major release). So for Play Store, select the required API level—but ensure your Unity version supports it. Otherwise, update Unity.
6. What if the error appears again in the future?
Answer: Just reduce your Target API Level again or update Unity to the latest version that supports newer SDK levels.
Additional Tip
If you frequently build Android APKs on Unity, always check:
- Your Unity version
- Installed Android Build Support
- JDK version included with Unity
- Whether your project uses old plugins
Sometimes outdated plugins can also trigger build errors. Keeping Unity modules updated helps avoid future issues.
Conclusion
The “java.lang.UnsupportedOperationException: This feature requires ASM7” error looks complicated, but the solution is one of the simplest fixes in Unity: just reduce the Target API Level by one step. This brings the API version back into Unity’s compatibility range and allows the Android build to complete successfully.
By following the exact steps explained in this guide, you can fix the issue in less than 2 minutes—no reinstallation, no complex debugging, and no advanced settings required.
If you regularly face Unity build errors, make sure to keep your SDK tools updated and always double-check your API settings before building.
