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How to Fix the 'Stylesheet is Missing' Error in Your Twenty Ten Child Theme

23 threads Sep 9, 2025 Theme → Twenty ten

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Creating a child theme for the Twenty Ten theme is a fundamental and recommended practice for making customizations. However, a common and frustrating roadblock many users hit is the error message: The following themes are installed but incomplete. Themes must have a stylesheet and a template. Stylesheet is missing.

This error prevents you from activating your new child theme, halting your progress. Based on community reports, this issue is almost always caused by a simple mistake in the child theme's setup rather than a bug in the Twenty Ten theme itself.

Why This Error Happens

WordPress requires two essential files to recognize a folder as a valid theme: a style.css file and a index.php file. The "stylesheet is missing" error means WordPress cannot find a properly formatted style.css file in your child theme's directory. The most common reasons are:

  1. Incorrect File Name: The file must be named exactly style.css.
  2. Syntax Error in the Header Comment: The metadata comment at the top of the style.css file is malformed, missing a required field, or contains smart quotes.
  3. File Permissions: The web server does not have read permissions for the file.
  4. Incorrect Directory Location: The child theme folder is not placed in the /wp-content/themes/ directory.

How to Fix It: A Step-by-Step Guide

Follow these steps to resolve the issue and successfully create your Twenty Ten child theme.

Step 1: Verify the Folder and File Structure

Ensure your child theme is set up with the correct structure. It should look like this:

/wp-content/themes/
    ├── twentyten/          (Parent theme)
    │   ├── style.css
    │   ├── index.php
    │   └── ...
    └── twentyten-child/    (Your child theme folder)
        ├── style.css      (Your child theme's stylesheet)
        └── functions.php  (Optional, but recommended)

Step 2: Create a Correctly Formatted style.css File

The content of your style.css file is critical. It must begin with a specific header comment. Use a plain text editor like Notepad++ or Visual Studio Code to create this file; do not use rich-text editors like Microsoft Word, as they can insert invalid characters.

Copy and paste the following code exactly into your style.css file. Pay close attention to the use of straight quotes (' and ") instead of curly or “smart” quotes.

/*
Theme Name: Twenty Ten Child
Theme URI: http: //example.com/
Description: A child theme of the default Twenty Ten WordPress theme.
Author: Your Name
Author URI: http: //example.com/about/
Template: twentyten
Version: 1.0.0
*/

@import url("../twentyten/style.css");

/* =Theme customization starts here
-------------------------------------------------------------- */
/* Add your custom CSS rules below this line */

Key Points:

  • Template: This line is the most important. It must exactly match the directory name of the parent theme, which is twentyten (all lowercase).
  • @import Rule: This line loads the parent theme's styles. Ensure the path is correct.

Step 3: Upload and Activate

Once you have created the style.css file with the correct header, upload the entire twentyten-child folder to your server's /wp-content/themes/ directory.

Log in to your WordPress dashboard, navigate to Appearance > Themes. You should now see your "Twenty Ten Child" theme available. Click "Activate".

What to Do If the Error Persists

If you still see the error after following the steps above, try these advanced troubleshooting tips:

  • Check File Permissions: Using your hosting control panel or an FTP client, check the permissions of the style.css file. It should typically be set to 644.
  • Create an index.php File: While a child theme should inherit the parent's index.php, creating a bare-bones one in your child theme folder can sometimes resolve the error. Simply create a new file named index.php and add this single line: <?php // Silence is golden.
  • Enable Debugging: Add define('WP_DEBUG', true); to your wp-config.php file. This might reveal a more specific error message that can help pinpoint the problem.

By carefully checking your file name, header comment syntax, and directory structure, you can overcome this common error and start customizing your Twenty Ten theme safely with a child theme.

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