Fixing Vungle SDK "Ad Not Available" & Error 10001 (No Fill)

There is nothing more frustrating in mobile app monetization than a silent ad network. You have integrated the Vungle SDK (now part of Liftoff), initialized it successfully, and set up your placements. Yet, when you attempt to display an interstitial or rewarded video, you hit a wall: Error 10001 or a persistent false return on isCachedAdAvailable.

For developers and monetization managers, this isn't just a bug—it represents a direct leak in potential revenue.

When the Vungle SDK returns VungleException.NO_SERVE (Error 10001), it explicitly means the server could not provide an ad for the specific request. While this can sometimes be a legitimate lack of inventory, a constant Error 10001 during development or production usually indicates a specific integration flaw.

This guide provides a rigorous technical breakdown of why this happens and how to fix it using modern Android (Kotlin) and iOS (Swift) implementations.

Root Cause Analysis: The Mechanics of "No Fill"

To fix the error, you must understand the architecture of the Vungle SDK. Unlike some display ad networks that load content instantly via WebView, Vungle relies heavily on precaching.

When you trigger a load, the SDK requests assets (video, end card, assets) from the edge server. Until every byte of that creative is downloaded and hashed on the local device storage, the ad is not "available."

The three most common technical reasons for Error 10001 are:

The Race Condition: Your code attempts to play an ad before the asynchronous download cycle has completed.
Test Mode Mismatch: The Vungle algorithm is designed to optimize revenue. If you request live ads on a test device with no behavioral history, the algorithm may refuse to bid (No Fill), thinking the traffic is low quality.
Contextual Data Failure: In modern implementations (post-GDPR/CCPA), if you fail to pass consent flags or clean context data, the ad server may reject the bid request entirely to avoid compliance risks.

Phase 1: The Configuration Checklist

Before refactoring code, eliminate the configuration variables. 90% of "No Fill" issues in the development environment stem from these two settings.

1. Enable Test Mode Explicitly

Live ad inventory fluctuates. If you are debugging, you must set your app to Test Mode in the Vungle Dashboard.

Navigate to the Vungle Dashboard.
Select your Application.
Toggle "Test Mode" to Active.
Note: It may take up to 30 minutes for this setting to propagate to the SDK.

2. Verify Placement Reference IDs

A common mistake is confusing the Placement Name (e.g., "Level Complete") with the Reference ID (e.g., DEFAULT-12345).

The SDK only accepts the Reference ID.
Ensure the placement is "Active" and "Cached" in the dashboard.
Ensure you are not mixing Android Placement IDs with iOS code, or vice versa.

Phase 2: Fixing the Race Condition (Android/Kotlin)

The legacy method of checking Vungle.canPlayAd() inside a button click is deprecated logic. It leads to missed opportunities because it is a passive check.

Instead, you must implement an active listener that reacts immediately when the ad server confirms the asset is cached.

The Problematic Pattern

// DON'T DO THIS
button.setOnClickListener {
    if (Vungle.canPlayAd(placementId)) { // Likely false
        Vungle.playAd(placementId, null, null)
    } else {
        Vungle.loadAd(placementId, object : LoadAdCallback { ... })
    }
}

The Correct Implementation

We will use the LoadAdCallback properly to separate the loading logic from the presentation logic.

import com.vungle.warren.Vungle
import com.vungle.warren.LoadAdCallback
import com.vungle.warren.PlayAdCallback
import com.vungle.warren.error.VungleException

class AdManager {

    private val placementId = "YOUR_PLACEMENT_ID"

    // Call this as early as possible (e.g. Activity onCreate)
    fun loadAdAsset() {
        if (Vungle.canPlayAd(placementId)) {
            println("Ad is already cached and ready.")
            return
        }

        Vungle.loadAd(placementId, object : LoadAdCallback {
            override fun onAdLoad(id: String) {
                // SUCCESS: The asset is on disk.
                // Now you can enable your "Show Ad" button
                println("Ad Loaded for placement: $id")
            }

            override fun onError(id: String, exception: VungleException) {
                // FAILED: Inspect exception.getExceptionCode()
                if (exception.exceptionCode == VungleException.NO_SERVE) {
                    println("Error 10001: Server returned no ads. Retrying in 30s...")
                    // Implement exponential backoff retry logic here
                }
            }
        })
    }

    fun showAd() {
        if (Vungle.canPlayAd(placementId)) {
            Vungle.playAd(placementId, null, object : PlayAdCallback {
                override fun onAdStart(id: String) {}
                override fun onAdEnd(id: String, completed: Boolean, isCTAClicked: Boolean) {
                    // Preload the NEXT ad immediately after the current one finishes
                    loadAdAsset() 
                }
                override fun onAdEnd(id: String) {}
                override fun onAdClick(id: String) {}
                override fun onAdRewarded(id: String) {}
                override fun onAdLeftApplication(id: String) {}
                override fun onError(id: String, exception: VungleException) {}
                override fun onAdViewed(id: String) {}
            })
        }
    }
}

Phase 3: Fixing the Logic (iOS/Swift)

On iOS, the concept is identical, but the implementation relies on the VungleSDKDelegate. A common error here is failing to reset the delegate or attempting to load an ad while one is already caching (Auto-Caching).

If you are using a placement marked as Auto-Cached in the dashboard, do not manually call loadPlacement. The SDK handles this automatically. Calling load manually on an auto-cached placement can cause conflicting states resulting in errors.

For non-auto-cached placements (most interstitials):

import VungleSDK

class AdController: NSObject, VungleSDKDelegate {
    
    let sdk = VungleSDK.shared()
    let placementID = "YOUR_PLACEMENT_ID"
    
    override init() {
        super.init()
        sdk.delegate = self
    }
    
    func requestAd() {
        do {
            // rigorous check to prevent redundant network calls
            if sdk.isAdCached(forPlacementID: placementID) {
                print("Ad already available.")
                return
            }
            
            try sdk.loadPlacement(withID: placementID)
        } catch let error as NSError {
            print("Unable to load placement: \(error.localizedDescription)")
        }
    }
    
    // MARK: - VungleSDKDelegate
    
    func vungleAdPlayabilityUpdate(_ isAdPlayable: Bool, placementID: String?, error: Error?) {
        guard let id = placementID, id == self.placementID else { return }
        
        if let error = error {
            // Deep dive into the error code
            let nsError = error as NSError
            if nsError.code == 10001 { // VungleSDKErrorNoServe
                print("10001: No Fill. Check Test Mode or Geo-Location.")
            }
        }
        
        if isAdPlayable {
            print("Asset downloaded. Ready to present.")
            // Enable your UI button here
        }
    }
    
    func presentAd(from viewController: UIViewController) {
        if sdk.isAdCached(forPlacementID: placementID) {
            do {
                try sdk.playAd(viewController, options: nil, placementID: placementID)
            } catch {
                print("Error playing ad: \(error)")
            }
        }
    }
}

Phase 4: The Compliance Gap (GDPR/CCPA)

Modern ad networks (including Vungle) have strict compliance filters. If you are testing in the EU or California (or using a VPN tunneling there) and you do not pass consent, the ad server may drop your request silently or return Error 10001.

You must pass the consent status before initializing the SDK or requesting ads.

Android Consent Update

// 1. Consent Status (GDPR)
Vungle.updateConsentStatus(Vungle.Consent.OPTED_IN, "1.0.0")

// 2. CCPA Status (US Privacy String)
Vungle.updateCCPAStatus(Vungle.Consent.OPTED_IN)

iOS Consent Update

// 1. Consent Status (GDPR)
VungleSDK.shared().update(VungleConsentStatus.accepted, consentMessageVersion: "1.0.0")

// 2. CCPA Status
VungleSDK.shared().update(VungleCCPAStatus.accepted)

Advanced Debugging: Traffic Inspection

If you have followed the steps above and still receive Error 10001, you need to verify the network traffic. Logs can be misleading; HTTP responses are not.

Use a proxy tool like Charles Proxy or Proxyman to inspect the traffic from your device.

Filter traffic for vungle.com.
Look for the /request or /ads endpoint.
Inspect the Request Body:
- Is the placement_id correct?
- Is the bundle_id matching your dashboard?
Inspect the Response:
- 200 OK with Empty Body: The server received your request but has no inventory for you. This is a "True No Fill." (Solution: Check eCPM floors, broaden Geo targeting).
- 400 Bad Request: Your integration is sending invalid data.
- 403 Forbidden: Your account is inactive or the App ID is disabled.

Conclusion

Error 10001 is rarely a random occurrence. It is a deterministic response indicating that the ad server cannot fulfill the request based on the parameters provided.

By forcing Test Mode during development, implementing asynchronous listeners rather than polling for availability, and ensuring strict privacy compliance, you can virtually eliminate false-negative "No Fills."

If the error persists in production only, consider implementing a waterfall mediation layer (like IronSource or MAX) to ensure that if Vungle fails to fill, another network can capture the impression.

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