How to fix white space issue in WordPress

Hira Ansari | June 23, 2024

The issue of a blank first line causing a white space error in a custom-coded WordPress theme is often related to unwanted spaces or new lines before the opening <?php tag in your theme files. Here’s a step-by-step approach to identify and resolve the issue:

Check the Theme’s Files:
- Open each PHP file in your theme’s directory, especially functions.php, header.php, footer.php, index.php, and page.php.
- Ensure that there are no spaces or new lines before the opening <?php tag at the very beginning of each file.
Check for Extra Spaces After Closing PHP Tags:
- Ensure there are no extra spaces or new lines after closing ?> tags, particularly in functions.php. Although it’s generally best practice to avoid closing ?> tags in purely PHP files, if they exist, make sure there are no trailing spaces.
Use an IDE or Text Editor:
- Use a code editor with the ability to show invisible characters (like Sublime Text, Visual Studio Code, or PHPStorm). This feature helps identify unintended spaces or new lines.
Check the wp-config.php File:
- Ensure there are no spaces or new lines before the opening <?php tag in wp-config.php.
Check for Plugins:
- Sometimes, plugins can cause white space issues. Deactivate all plugins temporarily and see if the problem persists. If it resolves, reactivate them one by one to identify the culprit.
Use an Output Buffering Technique:
- Implement output buffering in your functions.php file to prevent white space errors:
  php ob_start();

Here is a quick example of how to use an IDE or text editor to check for these issues:

Using Visual Studio Code:

Open the Theme Directory:
- Open Visual Studio Code and navigate to your theme’s directory.
Show Whitespace Characters:
- Go to View > Render Whitespace and select All or Boundary. This setting will show all spaces, tabs, and new lines.
Check Each File:
- Open each PHP file and ensure no spaces or new lines exist before the opening <?php tag and after closing ?> tags.

Using Sublime Text:

Open the Theme Directory:
- Open Sublime Text and navigate to your theme’s directory.
Show Whitespace Characters:
- Go to View > Show White Space. This will highlight spaces and tabs in your files.
Check Each File:
- Open each PHP file and ensure no spaces or new lines exist before the opening <?php tag and after closing ?> tags.

Additional Tip:

Use a File Comparison Tool:
- If you have a known good copy of your theme, use a file comparison tool (like diff in Unix or comparison features in IDEs) to compare your current theme files against the known good ones to spot any differences, including white space issues.

By thoroughly checking each file and using the right tools to identify hidden white spaces, you should be able to pinpoint and fix the issue causing the white space error in your custom WordPress theme.