iOS - Facebook Login Error - Unknown Error building URL (com.facebook.sdk.core error 3)

Question

I am using Facebook login for my iOS app being developed for iOS 8 and onwards. (Latest Facebook SDK is being used)

I have followed all the essential steps described by the Facebook official guide. However, when I click the login button it gives me the following error:

Unknown Error building URL (com.facebook.sdk.core error 3)

I have checked, to look what I might have done wrong, but everything seems as per guide, and I have been stuck here for a day.

Code for FB Login Delegate:

class FBLoginDelegate: NSObject,  FBSDKLoginButtonDelegate  {


func loginButton(loginButton: FBSDKLoginButton!, didCompleteWithResult result: FBSDKLoginManagerLoginResult!, error: NSError!){
    if(error == nil){
        print("Logged In from Btn")
    }else{
        print("Error: \(error.localizedDescription)") //Here it gives the error 
    }

}
}

Code for FB login button:

      var fbLoginBtnDelegate = FBLoginDelegate()
    let fbBtnWidth = self.view.bounds.width - (self.fbContainerLeftConstraint.constant + self.fbContainerRightConstraint.constant)
    let fbLoginButton = FBSDKLoginButton(frame: CGRectMake(0,0,fbBtnWidth,self.fbButtonContainer.bounds.size.height))

    self.fbButtonContainer.addSubview(fbLoginButton)
    fbLoginButton.readPermissions = ["public_profile", "user_friends", "email", "user_birthday"]
    fbLoginButton.delegate = fbLoginBtnDelegate

Please provide the code around where your error is occuring. — Sumner Evans, Feb 07 '16 at 00:49
Updated with code, but its just something very simple, as described in the documentation, I don't know whats going wrong. Please help — Muhammad Sadiq Alvi, Feb 07 '16 at 01:10
There has been a new release (v4.10.0) of the iOS SDK since you posted this, can you upgrade and try again? Also, is this happening on a device, in the simulator, with iOS 8/9? — Björn Kaiser, Mar 07 '16 at 17:43

David Liu · Answer 1 · 2019-01-09T20:07:58.413

64

If you upgraded the Facebook iOS SDK to version 4.39.0, there is a bug that causes this error. Downgrade to 4.38.1 will help you solve this problem. Be sure to downgrade both FBSDKCoreKit and FBSDKLoginKit.

pod 'FBSDKCoreKit', '~> 4.38.0'
pod 'FBSDKLoginKit', '~> 4.38.0'

Be sure to clean the build folder and re-build the SDK.

update: This bug has been fixed in 4.39.1 SDK release. https://developers.facebook.com/docs/ios/change-log-4x/

edited Jan 09 '19 at 20:07

answered Dec 09 '18 at 15:01

David Liu

952
7
15

2

Nice catch David and thanks for specifying the CocoaPod libraries. – xdeleon Dec 10 '18 at 03:35
No problem! Glad I can help. – David Liu Dec 10 '18 at 07:07
Solved it for us as well. Also would like to add that we tried a bunch of other things such as using `FBSDKSettings.setAppId`, changing display name etc but the only thing that worked was to downgrade. – Simon Bengtsson Dec 11 '18 at 11:16
Where is the doc or forum that says this is a bug from FBSDK v4.39.0? Url please – Crono Dec 11 '18 at 15:52
1

Might be related to this https://github.com/facebook/facebook-objc-sdk/commit/fe67bdb3f72a2e69422b2f609bc871c1dba2005a – Simon Bengtsson Dec 12 '18 at 00:13
1

Great! Has anyone forwarded this to Facebook to make them aware? – Chris Prince Dec 12 '18 at 05:11
Not sure what the best forum is to make them aware, but should effect everyone with latest sdk version? – Simon Bengtsson Dec 13 '18 at 07:33
1

You're a life saver, was really banging my head against a wall on this one – Brian Redd Dec 25 '18 at 03:10
Life and time saver. I updated Pods on 23rd December, and checked only today on Xmas and it was not working. Now reverted back and it is working fine. – zeeshan Dec 25 '18 at 17:17
3

the issues have been fixed on 4.39.1 – Nithin Michael Jan 09 '19 at 13:38
This still occurs with 4.39.1 for me. – Tamás Sengel Jan 16 '19 at 16:29
@TamásSengel, Be sure to clean the build folder and re-build the SDK in Xcode. – David Liu Jan 17 '19 at 09:51

score 7 · Answer 2 · answered Dec 14 '18 at 07:13

This is a Facebook SDK bug in version 4.39.0 which is causing this error. In order to solve this bug, simply downgrade both CoreKit and LoginKit to 4.38.0, clear derived data as well as clean build folder (CMD + OPTION + SHIFT + K). Whereas 4.38.1 also works fine.

pod 'FBSDKCoreKit', '~> 4.38.0'
pod 'FBSDKLoginKit', '~> 4.38.0'

If you are using FacebookCore and FacebookLogin then do like the following.

pod 'FacebookCore'
pod 'FacebookLogin'
pod 'FBSDKCoreKit', '~> 4.38.0'
pod 'FBSDKLoginKit', '~> 4.38.0'

the issues have been fixed on 4.39.1 – Nithin Michael Jan 09 '19 at 13:38 — Nithin Michael, Jan 09 '19 at 13:38

score 2 · Answer 3 · answered Mar 09 '16 at 16:32

For me, the problem was that the Facebook App ID indicated in CFBundleURLTypes > CFBundleURLSchemes in Info.plist were spelled out incorrectly.

I was importing the app ID from an .xcconfig file so that its underlying value changes depending on whether I'm running a Debug or Release scheme. However, when I printed out the plist file, there were unnecessary quotation marks around the app ID when read from the xcconfig files. For example, where the URL scheme should be fb012345678, it was fb"012345678".

I tried hardcoding the app IDs correctly into the Info.plist as stated in the Facebook guide, and the FBSDKLoginButton just worked. Safari came up to display the Facebook login screen. You don't have to hardcode the IDs though--just make sure they are substituted correctly in Info.plist.

score 1 · Answer 4 · edited Jun 20 '20 at 09:12

1

In terminal & Navigate to the project folder use

pod update

to update to current version 4.39.1

edited Jun 20 '20 at 09:12

Community

1
1

answered Jan 21 '19 at 13:10

Ionz

97
1
4

score 0 · Answer 5 · answered Dec 23 '18 at 19:41

I was following the react-native-fbsdk instructions in which you are supposed to copy Framework files/folders into the project. Thus, the Cocoapod approach given above didn't work for me.

What I did is remove the existing Framework files from the project (Right-click on Framework items -> Delete -> Yes Remove all), and then add the previous versions of the Frameworks again by downloading them from:

https://developers.facebook.com/docs/ios/downloads/

score 0 · Answer 6 · answered Feb 14 '19 at 04:50

I had to do two things to get this working.

1. Downgrade pods to

pod 'FBSDKCoreKit', '~> 4.38.0'
pod 'FBSDKLoginKit', '~> 4.38.0'

2. Remove -ObjC from other linker flags

Although this has been suggested in facebook developer portal. This was generating the below error:

com.facebook.sdk:FBSDKErrorDeveloperMessageKey=Unknown error building URL.

Hope this helps.

iOS - Facebook Login Error - Unknown Error building URL (com.facebook.sdk.core error 3)

6 Answers6

pod update

1. Downgrade pods to

2. Remove -ObjC from other linker flags

Linked