From approximately 19:20 June 20 UTC - 01:55 June 21 UTC (12:20pm - 6:55pm June 20 PDT), a portion of server-based calls made to the Measurement API were blocked due to an SSL authentication issue. The immediate issue has been mitigated.
SDK-based traffic appears to have not been impacted. Affected Measurement API calls to an affected host during this window would have experienced SSL errors.
Thank you for you understanding at this time. We will be reaching out to any affected advertisers. Should you have any queries, please don't hesitate to contact firstname.lastname@example.org.