Facebook-ios-sdk: FB login fails and locks up calling app

[Gillissie]

Checklist

• [x ] I've updated to the latest released version of the SDK
• [x ] I've searched for existing GitHub issues
• [ x] I've looked for existing answers on Stack Overflow, the Facebook Developer Community Forum and the Facebook Developers Group
• [x ] I've read the Code of Conduct
• [x ] This issue is not security related and can safely be disclosed publicly on GitHub

Environment

Describe your dev environment here, giving as many details as possible. If you have them, make sure to include:

• Xcode Version: 11.4.1
• Unity Version: 2018.4.22f1
• Mac OS version: 10.15.4
• iOS version: 13.4.1
• FB SDK version: Tried both 7.19.1 and 7.19.2

Goals

What do you want to achieve?
Simple facebook login from my iOS app, which has worked in the past. Retrieve the facebook ID.

Expected Results

What do you expect to happen?
A prompt appears, asking if you want to sign in with facebook. When you choose "Continue", it should show another UI that verifies your account info to sign in with, which you confirm. Then it returns to the original app, and provides facebook user data.

Actual Results

What actually happened? Can you provide a stack trace?
The first UI appears, I touch "Continue". The second UI slides up from the bottom of the screen, but then almost immediately disappears, leaving me back at my original app, but in a frozen state.
This is logged at startup by the FBSDK:
FBSDKLog: starting with Graph API v2.4, GET requests for /1229138037190390/model_asset should contain an explicit "fields" parameter
This is logged during the attempted sign-in:
_BSMachError: port d803; (os/kern) invalid capability (0x14) "Unable to insert COPY_SEND"

If I press the home button on my phone, then switch back to the app, the log shows this:
2020-05-15 15:37:47.320750-0500 swapretina[6123:2744779] Warning: Attempt to present on whose view is not in the window hierarchy!
and the app gets a FB login cancellation event. However, the app is still frozen.

Steps to Reproduce

What are the steps necessary to reproduce this issue?
Make a Unity project build using the versions of everything I mentioned above, and try it.

Code Samples & Details

Please provide a code sample, as well as any additional details, to help us track down the issue. If you can provide a link to a test project that allows us to reproduce the issue, this helps us immensely in both the speed and quality of the fix.

Note: Remember to format your code for readability:

There really is nothing special about my code to start the login process. It's been unchanged for over a year.
var perms = new List(){"public_profile"};
FB.LogInWithReadPermissions(perms, authCallback);

[advantage-software]

I'm seeing the same thing using Unity2019.3.14f1

[Gillissie]

Yeah, apparently it's a Unity bug in certain versions. I reverted my project to 2018.4.6f1 and it works fine.

[advantage-software]

We tracked it down to this setting in the ProjectSettings.asset file in the ProjectSettings folder:
iOSRenderExtraFrameOnPause: 0

If this item is set to 1, then Facebook login will launch and abruptly hide, then return you to the app in a locked up state

[jrgibson]

@Gillissie and @advantage-software thank you both for your posts on this. @advantage-software I tried setting iOSRenderExtraFrameOnPause to 0, but I'm still getting the same error. I'll try reverting to 2018.4.6f1 as Todd suggested. Right now, I'm on 2018.4.23f1.

[jrgibson]

Update: I regressed to Unity 2018.4.6, and it worked! This is, of course, still a problem because I can't use the latest 2018.4 LTS, but for now, my app can run and use the Facebook SDK.

[Gillissie]

Update: I reported this bug to Unity, and they needed repro steps, so I created an entire set of steps. However, along the way, I also got 2018.4.22 to work. It seemed that if I changed a couple of player settings, then changed them back, it sort of fixed itself. It seemed to be mainly tied to the .NET version. Change to 2.x, then back to 4.x and see if it works on 2018.4.22.

[footprint]

We tracked it down to this setting in the ProjectSettings.asset file in the ProjectSettings folder:
iOSRenderExtraFrameOnPause: 0

If this item is set to 1, then Facebook login will launch and abruptly hide, then return you to the app in a locked up state

thanks

[kiraeyoun]

We tracked it down to this setting in the ProjectSettings.asset file in the ProjectSettings folder:
iOSRenderExtraFrameOnPause: 0

If this item is set to 1, then Facebook login will launch and abruptly hide, then return you to the app in a locked up state

I changed iOSRenderExtraFrameOnPause 1 -> 0, then It works. Thank you

[almeynman]

We tracked it down to this setting in the ProjectSettings.asset file in the ProjectSettings folder:
iOSRenderExtraFrameOnPause: 0

If this item is set to 1, then Facebook login will launch and abruptly hide, then return you to the app in a locked up state

Worked for me too