Starting on April 22nd, 2014, a v201309 or v201402 AdGroupBidModifierService.mutate request will fail with a CriterionError and reason CANNOT_BID_MODIFY_CRITERION_TYPE if all of the following conditions are met for the same criterion:
  • The criterion is a Platform criterion for the mobile platform ID (30001)
  • The Campaign has a CampaignCriterion for the mobile platform criterion with a bidModifier set to 0 (this is displayed as a Bid adj. of -100% under Settings in the AdWords UI)
  • The AdGroupBidModifier has the same mobile platform criterion and attempts to set the bidModifier to any value other than 0
The AdWords API and UI will start rejecting such requests because allowing this combination could give the impression that the ad group will serve ads for the mobile platform criterion when in fact it will not.

For example, assume you create a campaign with a CampaignCriterion containing the following criterion and bid modifier:
<criterion xmlns:xsi=""
<!-- This will appear as "-100%" in the UI. -->
If you attempt to create an AdGroupBidModifier containing the following criterion and bid modifier for any ad group in the campaign on or after April 22nd, 2014, it will fail because the non-zero ad group bid modifier of 1.25 would have no effect:
<criterion xmlns:ns2=""
<!-- This will appear as "+125%" in the UI.  Any other non-zero
     value will also fail. -->
Before April 22nd, 2014, please take the following actions to ensure a smooth transition for your application:
  • Make sure that your application will be able to properly handle the error
  • Examine your existing campaigns and ad groups and address any bid modifiers that meet the conditions above
Not using bid adjustments in your campaigns and ad groups? Check out our bid modifiers guide to learn how to use this powerful feature of AdWords.

Still have questions? Feel free to visit us on the AdWords API Forum or our Google+ page.