When working with a WordPress child theme, you may suddenly encounter the warning: “This theme is broken. The parent theme is missing.” Even though the parent theme is already installed, WordPress insists it cannot be found. This issue is not a beginner mistake—it is a subtle but critical detail in how WordPress handles themes.
In this article, I explain the real cause of this error based on a real troubleshooting experience, and show the fastest way to fix it. Before blaming functions.php, Gutenberg, or single.php, there is one essential thing you must check.
The conclusion is simple: the Template value in the child theme’s style.css did not match the parent theme’s directory name. WordPress does not use the theme’s display name. It strictly relies on the folder name.
In my case, the parent theme directory was named “picostrap5”. However, the admin warning repeatedly told me to install the “picostrap” parent theme. This mismatch caused a lot of confusion and led me to investigate completely unrelated areas of the code.
Here is the correct structure of a child theme header:
/*
Theme Name: Zidooka Child
Template: picostrap5
Version: 1.0.0
*/
The value of Template must exactly match the parent theme’s folder name. If the folder is named picostrap5, then Template must also be picostrap5. Any difference—even if the theme name looks correct—will cause WordPress to treat the theme as broken.
What makes this issue particularly difficult is that the site often still appears to work. WordPress does not throw a fatal error. Instead, it enters a partially broken state. In this state, you may see issues such as:
・Featured image settings disappearing from the editor ・add_theme_support(‘post-thumbnails’) appearing not to work ・Missing Gutenberg options ・Unstable editor or theme behavior
This is exactly what happened in my case, which is why the root cause was so hard to identify.
The fix is straightforward. Install the correct parent theme and ensure that the Template value in style.css exactly matches the parent theme’s directory name. The parent theme does not need to be activated; it only needs to exist.
After fixing this and reloading the admin screen, the warning disappears and all related features return to normal.
Child themes are powerful, but they require precise configuration. Confusing a theme’s display name with its directory name is a surprisingly common mistake, especially among experienced developers.
If you are seeing the “parent theme is missing” error, check the Template value first. It may save you hours of unnecessary debugging.