I had not realised that this blog's URL is considered unsecured when it is accessed by others. I only knew about it when I tried to visit the site via links that I had placed in my Facebook and Instagram profiles. Clicking on the links would show a warning or simply do nothing.
I have checked my blogspot settings and chose the automatic https redirection option but still, there are errors. A fellow blogger has advised that individual links that I inserted in the blog may also be the cause of errors.
So, for the next few weeks, I'll try tweaking this blog's layout in search of the offending codes or links. I apologise if you see different or simplified layouts that change periodically.
Thank you.
Update 26.06.2021 : This is looking like a labouriously long process. I've run the 'Why No Padlock' online checking tool. The results say my SSL certificate is valid.
I've removed all my sidebar gadgets which are not original Blogger gadgets and may contain unauthorised javascripts. Still no luck.
Another suggested process is to look at each individual post and remove any missing or expired links. Now this is going to take some time... sigh...
Update 23.07.2021 : I have just finished reviewing the 11 blog posts in the month of April 2008 which was when I started blogging. The very first post contained a link to George Carlin's website which no longer exists. I have removed the link. Other posts have photographs that are apparently linked to bp3.blogger pages which are not secure. This is a bit strange because all those pics are my originals (i.e. not copied from others). I have removed the said pics but re-inserted them directly from my PC. Let's see if this resolves the issue. Tough days ahead to review all the other pics in this 12-year old blog.