Debugging Google On-Device Conversion Measurement Setup on iOS

If iOS logs say that on-device conversion measurement could not start, verify the implementation before comparing campaign totals. A setup warning and a gap between Google Ads and an attribution report are different problems.

Check which setup you implemented

Start with the Firebase on-device measurement setup guide. Match the instructions to the SDK and setup path you actually use. For the path that uses first-party user data, use the documented input type and method for a consented email address or phone number. Verify that the build includes the required SDK components, and that your code calls the method only when the correct input is available.

Reproduce the warning in one test build

Record the app version, SDK version, iOS version, and when the setup call runs. Confirm that the warning corresponds to this call rather than to another initialization step. Test with a known consent state; do not paste personal identifiers into a debugging log or support ticket.

Compare reports as a separate step

Once the setup works as expected, compare the same app, dates, conversion definition, and attribution window across reports. Note whether one system includes modeled results or uses different reporting dates. A difference alone does not identify an SDK problem or show that on-device measurement caused it. Start with a reproducible implementation check, then investigate the reporting scope independently.