How to Fix Unity Conversion Error: Unable to Convert Classes into Dex Format


This documentation post provides step-by-step instructions on how to fix the Unity conversion error “Unable to Convert Classes into Dex Format”. It also gives an overview of necessary components for debugging and explains relevant background information. Finally, it ends with an FAQ section to answer commonly asked questions.


The “Unable to Convert Classes into Dex” error is a frequent issue encountered when working with the Unity game engine. In order to properly debug this error, developers should be familiar with:

  • Unity game engine
  • the Android SDK
  • the Java Development Kit
  • and the Android Debug Bridge (ADB)

Step-by-Step Instructions

Check if java and adb are both installed. You can do this by typing “java -version” or “adb version” and seeing if any installed versions are displayed.

Check Android SDK Path: Make sure you have the Android SDK path correct in window > Preferences > External Tools. If you have the wrong path then change it.

Increasing Java Max Heap Size: Unity has a default maximum heap size of 1024MB, while the default maximum heap size in the Java Development Kit is 64MB. You may need to increase the max heap size. Refer to an instruction guide to learn how to do this.

Try recompiling your game code. The game code may be too large for the Android DEX format, so try to reduce the size of your game code. Refer to this Unity documentation for more information.

Running .bat files: Some .bat files have issues with compatibility. Review any .bat files in your project directory and make sure they are compatible with your platform. Refer to this article for help.


Q. What causes the “Unable to Convert Classes into Dex Format” error?
A. This error is usually caused by an incompatibility between the Java Development Kit and the Android SDK, a large game project file, or an issue with the .bat files.

Q. Is this error exclusive to Windows platforms?
A. No, this error can be encountered on other platforms.

Q. How can I reduce the size of my game project file?
A. Refer to the Unity documentation for more information.

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