This problem appears to be related to the Blogger rollout of SSL support, for our blogs, which is currently in progress. SSL, or Secure Socket Layer, represents the next step in blog / website security - a step which the Internet community has been taking, for many years.
Blogger has been using SSL (aka "HTTPS" login), in their dashboard, for several years.well known "mixed mode" warnings.
This site has insecure content.
Only secure content is displayed.
Firefox has blocked content that isn't secure.These are several examples of what were normal, years ago, on many websites. Blogger does not want our readers subject to needless confusion, from these warnings.