[Bug] Cloud functions can only be invoked from Unity main thread

[Moe-Baker]

Description

Cloud functions can only be invoked from the main thread due to attaching the X-Firebase-AppVersion header using the value supplied from UnityEngine.Application.version, accessing that value from outside the main thread will cause an exception.
These non-main-thread function invocations used to work on SDK v13.5.0, I believe the recent functions serialization logic in SDK v13.10.0 probably caused this.

Reproducing the issue

Call any cloud function from outside the main thread

Firebase Unity SDK Version

13.15.0

Unity editor version

6000.3.8f1

Installation Method

Unity Package Manager

Problematic Firebase Component(s)

Functions

Other Firebase Component(s) in use

Analytics, Authentication, Crashlytics, Firestore, Messaging, Remote Config, Storage

Additional SDKs you are using

No response

Targeted Platform(s)

Android, Apple Platforms

Unity editor platform

Windows

Scripting Runtime

IL2CPP

Release Distribution Type

Pre-built SDK from https://firebase.google.com/download/unity

Relevant Log Output

UnityException: get_version can only be called from the main thread.
Constructors and field initializers will be executed from the loading thread when loading a scene.
Don't use this function in the constructor or field initializers, instead move initialization code to the Awake or Start function.
UnityEngine.Application.get_version () (at <00000000000000000000000000000000>:0)
Firebase.Internal.HttpHelpers.SetRequestHeaders (System.Net.Http.HttpRequestMessage request, Firebase.FirebaseApp firebaseApp, System.String authPrefix, System.Boolean limitedUseAppCheckTokens) (at ./Library/PackageCache/com.google.firebase.app@f37c8a4637b5/Firebase/FirebaseApp/Internal/HttpHelpers.cs:35)

If using CocoaPods for Apple platforms, the project's Podfile.lock

No response

[niccolo-hare]

Hi @Moe-Baker, thanks for bringing this to our attention. I did some testing, and it does look like you can invoke Cloud Functions outside of the main thread if you use an SDK version that's older that v13.10.0 (I tested it on 10.9.0). But I'm not quite sure if this is caused by the recent changes to the serialization logic of the Cloud Functions SDK or by some other issue with the SDK. Let me try reaching out to our engineers for their insights, and for confirmation if this is a bug.

I'll update you as soon as I have more information that I could share. Let me know if you have questions.

[niccolo-hare]

Hi @Moe-Baker, just wanted to share an update with you. I was able to confirm with the engineers that this is a bug. Looks like our change in 13.10.0 required functions to be called on the main thread. We're currently working on a fix, but I can't provide you with a schedule or time frame of when it would be released. Though I would recommend checking our release notes for further updates.

Thanks again for flagging this. Let me know if you have any additional questions or clarifications.