To help spot and fix some of these errors, we're releasing a mixed content warning tool that alerts you to possible mixed content issues in your posts, and gives you the option to fix them automatically before saving.
To use the tool, turn on HTTPS for your blog, open the Blogger editor HTML view, and click Save or Publish. If the editor detects any errors they will be shown above the editor, along with the option to fix the errors found.
Happy blogging!
Posted by Shweta Karwa, Software Engineer, Security.