Old bug reappeared in Remote Config (was fixed in #4677)

[abrivle]

Description

I'm experiencing a bug that was previously fixed in Firebase iOS SDK but seems to have reappeared.

Here is the link to the old issue where this was fixed: #4677.
The exact same behavior is now happening again.

Reproducing the issue

No response

Firebase SDK Version

11.8.1

Xcode Version

16.2

Installation Method

Swift Package Manager

Firebase Product(s)

Remote Config

Targeted Platforms

iOS

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.

[rizafran]

Thanks for reporting, @abrivle. Could you share your detailed repro steps that triggers the error?

[abrivle]

@rizafran, just like in the related issue:

• Run app (remote config fetched success)
• Backup iOS system
• Restore backup iOS system
• Run app (remote config gives 0 keys)

I noticed something was wrong with my app after I upgraded to a new device. I found an issue (#4677), which I was able to reproduce again on my old device by following the steps above.

[rizafran]

Thanks for sharing your repro steps, @abrivle. I've raised this to our engineers and see what we can do here.

[ivan-gaydamakin]

On last version Firebase ios sdk 11.10.0, issue is still persist.

And when Firebase tried to fetch new config, they received:

Tried to delete installationID and re-fetch config, it didn't help.
Helps only to remove app and install it again.

UPD:
After some investigations, we have option:

• Add new feature flag on Firebase console :D

Also I reproduced this issue manually, just enough to truncate "main" and "main_active" tables in RemoteConfig.sqlite3.

[ivan-gaydamakin]

So, after more investigations, I found a fix:

Before FirebaseApp.configure() we just remove Firebase settings from UserDefaults and use force fetch: remoteConfig.fetch(withExpirationDuration: 0)

My prototype looks like that:

func findRemoteConfigDatabaseURL() -> URL? {
    let fileManager = FileManager.default
    do {
        // Get the Application Support directory URL
        let appSupportURL = try fileManager.url(
            for: .applicationSupportDirectory,
            in: .userDomainMask,
            appropriateFor: nil,
            create: false
        )
        // Append the relative path for the RemoteConfig database file
        let remoteConfigURL = appSupportURL
            .appendingPathComponent("Google/RemoteConfig/RemoteConfig.sqlite3")

        // Check if the file exists at the constructed URL
        guard fileManager.fileExists(atPath: remoteConfigURL.path) else {
            print("RemoteConfig.sqlite3 not found at path: \(remoteConfigURL.path)")
            return nil
        }
        return remoteConfigURL
    } catch {
        print("Error retrieving Application Support directory: \(error.localizedDescription)")
        return nil
    }
}


 do {
            if let url = findRemoteConfigDatabaseURL() {
                let db = try DBManager(fileURL: url)
                let isEmpty = try db.isRemoteConfigKeysEmpty()
                let google = UserDefaults(suiteName: "group.BUNDLE_ID_OUR_APP.firebase")
                if isEmpty {
                    print("Detected bad config, remove firebase userDefaults")
                    google?.removeObject(forKey: "__FIRAPP_DEFAULT")
                }
            }
        } catch {
            print("error", error)
        }

        if FirebaseApp.app() == nil {
            FirebaseApp.configure()
        }

I used Sqlite native library to check RemoteConfig.sqlite3 file, it has records in main or not.
If it's empty, just remove __FIRAPP_DEFAULT and now it works.

P/S: replace BUNDLE_ID_OUR_APP to your bundle id of course.
P/S2: DON'T remove that object from UserDefaults after configured FirebaseApp, it can make a lot of bugs.

Continue investigations with real test case, maybe will found something new.

UPD:
hm, strange, after backup/restore with sdk 11.8.1, configuration successfully downloaded.
But anyway, sometimes I got that issue on production by other users, when User cannot fetch new logs.

SDK version 11.8.1 too. (I made special key, that key has value True, when I got that issue with empty configs, our I will send non-fatal exception about that.)
No any errors by firebase before / after was (we also logged in all errors by firebase fetch / active).

And repro on Appium UI Testing sometimes...

Just for information: after backup/restore - Google/RemoteConfig/RemoteConfig.sqlite3 in applicationSupportDirectory is removed and Firebase's UserDefaults still exists

[ivan-gaydamakin]

But bug still persist. Received new report by different user: they got that bug when migrated from old to new iPhone (without PC, that case I didn't check). So... a little bit different repro case :) @rizafran

[rizafran]

Hi, I already filed a bug for this, internally tracked at b/409785001.