We wanted to let you know that yesterday at around 2pm PST, a bug in our system caused less relevant contextually-targeted ads to appear for approximately 10 hours. You were still credited for all valid clicks and impressions on the ads which appeared on your sites, but this bug may have impacted your overall AdSense for content revenue if you had visitors to your pages during these hours. Please note that because we're unable to determine which ads would have been viewed or clicked on by visitors to your sites in the absence of the bug, we will not be manually adjusting yesterday's earnings.

Our engineers have now resolved the issue and have confirmed that ad targeting has returned to normal. We apologize for this issue; please know that our engineers are performing a thorough analysis of what occurred and will make changes to prevent similar problems from happening in the future.