[Bug] Unity 2021.2 "Internal build system error. Backend exited with code" error after import Firebase SDK 8.8.0

[REQUIRED] Please fill in the following fields:

• Unity editor version: Unity 2021.2.9f1
• Firebase Unity SDK version: 8.8.0
• Source you installed the SDK: Unity Package Manager by point to the path where tar file is. (tar file and how to install SDK with tar file is follow the guide here: https://developers.google.com/unity/instructions#install-tgz)
• Problematic Firebase Component: com.google.firebase.app (Auth, Database, etc.)
• Other Firebase Components in use: Auth, Database, Storage, messaging, remote-config, crashlytics, analytics (Auth, Database, etc.)
• Additional SDKs you are using: External dependency manager (Facebook, AdMob, etc.)
• Platform you are using the Unity editor on: MacBook Pro with M1 chip and OS version is 12.3 Beta （The OS version may not a reason due to the same issue occur on macOS 12.2）
• Platform you are targeting: Android/iOS (iOS, Android, and/or desktop)
• Scripting Runtime: IL2CPP (Mono, and/or IL2CPP)

[REQUIRED] Please describe the issue here:

(Please list the full steps to reproduce the issue. Include device logs, Unity logs, and stack traces if available.)

Once I import the Firebase SDK the Unity Editor show the message likes “Internal build system error. Backend exited with code”, “Backend produced unparsable log entry” and then the compile backend of Unity Editor is totally crash so I cannot compile my game script after the script is modified.

Steps to reproduce:

Have you been able to reproduce this issue with just the Firebase Unity quickstarts (this GitHub project)? What’s the issue repro rate? (eg 100%, 1/5 etc)

1. Create empty Unity project and import Firebase SDK by tar file and EDM4U. (Basically I just import “com.google.firebase.app” package and issue comes)
2. Create a new .cs script and do some modify on the script.
3. Issue reproduce.
4. 100% reproduce.
5. Reproduced on Unity 2021.2.9, 2021.2.10

What happened? How can we make the problem occur? This could be a description, log/console output, etc.

If you have a downloadable sample project that reproduces the bug you’re reporting, you will likely receive a faster response on your issue.

Relevant Code:

// TODO(you): code here to reproduce the problem

[AlmostMatt]

Based on my testing so far, this issue does not occur when using the just-released version 8.10.0 of the Firebase Unity SDK I was able to just add the relevant 8.10.0 packages to a project that had been failing, restarted Unity, and then builds succeeded.

I’ll continue to look into why the issue occurs in 8.9.0, but in the meantime using 8.10.0 is a possible workaround

[korober]

Unity 2021.3 (Intel version) + Firebase 8.9.0 same issue (backend exited with code 2) Fixed with the workaround.