Keeping websites up-to-date can be harder than creating them in the first place. Things change on our side and things change on Google's side. We now spend 90% of our time browsing on secure websites, but there often remain non-secure images, charts, videos, and other pieces here and there where the link still starts with "http://", instead of "https://."
It's now time to clean up those links or risk Google blocking pieces of your site. Google published an announcement on October 3 warning that " mixed content" - content that is a mix of secure and non-secure items-, will start to see new warnings or even be blocked.Read More.
Follow this link for more information.
Non-secure resources can present a threat to privacy or security.
Be sure other resources are accurate
And while you're at it, check your Google Places, Bing Places and other web resources to make sure you still have correct phone numbers, open hours, and so on. Web users frequently find themselves relying on information published with Google Places, only to find that the restaurant is closed when they arrive or that the phone number is out of service.