If you are an old Tumblr user you might still find your Tumblr blog being marked as “not secure” on Google Chrome and other web browsers. The reason why your Tumblr blog is marked as “not secure” is because you haven’t enabled SSL on Tumblr to change the protocol of your Tumblr blog from HTTP to HTTPS.
Starting from version 68, Google Chrome has been marking all HTTP websites as “not secure” to protect internet users from accessing the safe websites. The step has been followed by other web browsers. Google Chrome and other modern browsers mark HTTP website as “not secure” because the communication protocol of HTTP is not encrypted so the transferred data is vulnerable to cyber crime. Conversely, HTTPS is safer than HTTP because the communication protocol is encrypted using TSL or SSL. On Google Chrome, HTTPS websites are marked with a padlock icon.
Tumblr itself already has a built-in SSL. New users don’t need to enable this feature manually since it has been enabled by default. Different story applies to old users. Some old users might need to enable this feature manually.
To enable the SSL feature on Tumblr, login to your Tumblr dashboard. Click the person icon on the upper right corner and select Settings.
Select the Tumblr blog you want to enable the SSL of.
Slide the button of Always serve blog over SSL on the Encryption section.
Done. Your Tumblr blog is now won’t be marked as “not secure” anymore. Please note that the Encryption section is not available for newer Tumblr users. All new Tumblr blogs will automatically be directed to HTTPS.