The Google Ads API is introducing a new error code, DEVELOPER_TOKEN_INVALID, in version v19.1 to specifically indicate authentication errors caused by an invalid developer token. Previously, such errors returned an OAUTH_TOKEN_HEADER_INVALID error, which was also used for other invalid request header values.
Versions prior to v19 handled invalid developer tokens with a DEVELOPER_TOKEN_NOT_APPROVED error. Users of version v19 will need to update to the latest client libraries after the v19.1 release, effective from April 28, 2025. This change aims to enhance the onboarding experience for new developers, while existing users are unlikely to be affected.
