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Use the Google sample ad unit ID that matches both your Unity app’s platform and its ad format. Ad Inspector error 2 means the device is not in test mode; error 3 means the inspector is already open. These are Ad Inspector errors, not ad-load error codes.
What are the AdMob test ad unit IDs for Unity?
Google provides separate sample IDs for Android and iOS, and each ID is tied to an ad format. Choose the column for your target platform and the row for the format you are testing.
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| Ad format | Android test ad unit ID | iOS test ad unit ID |
|---|---|---|
| App open | ca-app-pub-3940256099942544/9257395921 |
ca-app-pub-3940256099942544/5575463023 |
| Fixed-size banner | ca-app-pub-3940256099942544/6300978111 |
ca-app-pub-3940256099942544/2934735716 |
| Anchored adaptive banner | ca-app-pub-3940256099942544/9214589741 |
ca-app-pub-3940256099942544/2435281174 |
| Interstitial | ca-app-pub-3940256099942544/1033173712 |
ca-app-pub-3940256099942544/4411468910 |
| Rewarded | ca-app-pub-3940256099942544/5224354917 |
ca-app-pub-3940256099942544/1712485313 |
| Rewarded interstitial | ca-app-pub-3940256099942544/5354046379 |
ca-app-pub-3940256099942544/6978759866 |
| Native | ca-app-pub-3940256099942544/2247696110 |
ca-app-pub-3940256099942544/3986624511 |
These are sample ad units, not IDs connected to your AdMob account. Google says they show Google Ads only and instructs developers to replace them with their own ad unit IDs before publishing. See Google’s Unity test ads guide.
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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchHow do test ad unit IDs differ from test device IDs?
A test ad unit ID is a sample placement ID selected by platform and format. A test device ID identifies a device that is allowed to receive test ads while your app uses your own ad unit ID. They solve different testing needs and are not interchangeable.
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Android emulators and iOS simulators are automatically treated as test devices. For a newly configured test device, Google says test ads typically begin within 15 minutes, but setup can take up to 24 hours. Consult the test-device instructions if you are configuring a physical device.
What do Ad Inspector error codes 2 and 3 mean?
These codes describe why Ad Inspector itself cannot be opened:
- ERROR_CODE_NOT_IN_TEST_MODE (2): The device is not in test mode. Configure the device for test ads before trying to open Ad Inspector.
- ERROR_CODE_ALREADY_OPEN (3): Ad Inspector is already open. Close the current inspector instance before opening it again.
Google’s Ad Inspector error reference also lists internal error (0) and failed to load (1); the two above are the test-setup-related codes.
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How should you diagnose a failed ad load?
A failed request is a separate issue from an Ad Inspector error. In Unity, a load failure is delivered through the LoadAdError failure callback. Capture the domain, integer code, message, cause when present, and response information. Google notes that the domain distinguishes Google Mobile Ads SDK errors from mediation-defined errors; use the message and response details to investigate the cause.
See Google’s Unity ad load error guidance and Unity AdError API reference.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What changes when you test mediation or use Ad Inspector?
Mediation needs network-specific test setup
Google’s sample ad units show Google Ads only. To test mediation, configure test devices and test settings for the mediation networks involved. Mediated ads do not display the “Test Ad” label, so the label’s absence alone does not establish that an ad is a production ad. Google says test ads can be clicked safely, and their requests, impressions, and clicks do not appear in AdMob account reports. See the test ads guide.
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Choose the appropriate Ad Inspector testing mode
Ad Inspector supports in-context and out-of-context testing. Google recommends in-context testing for full parameter support. Out-of-context requests omit some app UI parameters, including child-directed treatment configuration, custom targeting, network extras, and different sizes. Details are in Google’s Ad Inspector testing guide.
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Single-ad-source testing applies to future ad requests. Ads already cached by the app may remain available, so Google recommends restarting the app after changing the test source.
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