Since WordPress began updating themes automatically in a recent release it has created some headaches for me. I often use some of the default themes on my websites but I do modifications to the CSS and some of the template files. WordPress got my tho with my pants down and deleted all my changes to these themes after updating automatically to the newer versions.
The trick I do to avoid this happening anymore is that I simply rename the folder of the theme in the wp-content folder on the server to something like my site name. I also change the title of the theme in the header in the style.css to completely rename the theme. These are the lines of code i change in the stylesheet:
Theme Name: WMWeblog
Theme URI: http://www.wmweblog.com/
Author: the WMWeblog.com
Author URI: https://www.wmweblog.com/
Description: WMWeblog theme is based on: (here comes the original description for the theme that has been changed)
After you do the two changes you will find that your website will display blank. Don’t worry tho you just need to go into the admin screen of your site and change your theme to the new theme you just created. Yes you did in fact create a new theme by doing these small changes. Could be good to know 🙂
Before I did this I tried using a plugin that was supposed to fix the problem but that did not work and the themes suddenly got updated overwriting my code once again. So now I do the mentioned actions on all the websites I change theme files on.