How to Fix the “Cannot Modify Header Information – Headers Already Sent By” Error on WordPress?

The “Cannot Modify Header Information – Headers Already Sent By” error is a common issue in WordPress, typically caused by whitespace or other characters being output before WordPress sends HTTP headers. Here’s how you can fix it:

  1. Check for whitespace before the opening tag:
    Similarly, make sure there’s no whitespace after the closing ?> tag in any of your PHP files. It’s often recommended to omit the closing ?> tag altogether to avoid this issue.
  2. Disable plugins and switch to a default theme:
    Deactivate all plugins and switch to a default WordPress theme like Twenty Twenty-One. If the error disappears, reactivate your plugins and theme one by one until you find the one causing the issue.
  3. Use a default WordPress file:
    Replace your current functions.php file with a fresh copy from the default WordPress installation. This can help if your current functions.php file has been corrupted.
  4. Check for BOM (Byte Order Mark):
    If you’re using a text editor to edit your files, ensure it’s not adding a BOM at the beginning of your PHP files. BOM can cause headers to be sent prematurely.
  5. Increase PHP memory limit:
    Sometimes, insufficient PHP memory can lead to this error. You can increase the PHP memory limit by adding the following line to your wp-config.php file:

    define('WP_MEMORY_LIMIT', '64M');
  6. Enable debugging:
    Add the following lines to your wp-config.php file to enable error logging and display:

    define( 'WP_DEBUG', true );
    define( 'WP_DEBUG_LOG', true );
    define( 'WP_DEBUG_DISPLAY', false );
  7. Check for any output before headers:
    Review your theme’s header.php file for any HTML or whitespace before the line.
  8. Use output buffering:
    You can use PHP’s output buffering functions to capture any output before headers are sent. Place the following code at the beginning of your functions.php file:

    ob_start();
  9. Check file encoding:
    Ensure that all your PHP files are saved in UTF-8 without BOM encoding. Some text editors, especially on Windows, may use different encodings by default.

After applying these steps, refresh your WordPress site to see if the error has been resolved. If it persists, you may need to consult with a developer or your hosting provider for further assistance.

How to Increase PHP Memory Limit?

You can try increasing the PHP memory limit in your server’s configuration or in your PHP script if it’s allowed. To do this:

In PHP Script (not recommended for production environments, but useful for testing):

Add the following line at the beginning of your PHP script to increase the memory limit:

ini_set('memory_limit', '256M'); // Set the memory limit to 256 megabytes

In Server Configuration (recommended for production environments):

Edit your PHP configuration file (php.ini) and increase the memory limit. Look for the memory_limit setting and change it to a higher value. For example:

memory_limit = 256M

After making this change, you’ll need to restart your web server (e.g., Apache or Nginx) for the new memory limit to take effect.

What is Software Testing Life Cycle (STLC)?

Software Testing Life Cycle (STLC) is a sequence of different activities performed during the software testing process.

Phases of STLC:

  1. Requirement Analysis:
    Requirement Analysis is the first step of Software Testing Life Cycle (STLC). In this phase quality assurance team understands the requirements like what is to be tested. If anything is missing or not understandable then quality assurance team meets with the stakeholders to better understand the detail knowledge of requirement.
  2. Test Planning:
    Test Planning is most efficient phase of software testing life cycle where all testing plans are defined. In this phase manager of the testing team calculates estimated effort and cost for the testing work. This phase gets started once the requirement gathering phase is completed.
  3. Test Case Development:
    The test case development phase gets started once the test planning phase is completed. In this phase testing team note down the detailed test cases. Testing team also prepare the required test data for the testing. When the test cases are prepared then they are reviewed by quality assurance team.
  4. Test Environment Setup:
    Test environment setup is the vital part of the STLC. Basically test environment decides the conditions on which software is tested. This is independent activity and can be started along with test case development. In this process the testing team is not involved. either the developer or the customer creates the testing environment.
  5. Test Execution:
    After the test case development and test environment setup test execution phase gets started. In this phase testing team start executing test cases based on prepared test cases in the earlier step.
  6. Test Closure:
    This is the last stage of STLC in which the process of testing is analyzed.

Does Mautic works with WordPress ?

Yes, Mautic can be integrated with WordPress. There are several benefits about this and integration is very easy as well. When integrating with WordPress the whole part of Landing pages creation can be moved to WordPress. Also the Forms requirements of WordPress can be fulfilled by Mautic. So conclusion is, Mautic and WordPress works well together and are very useful.

here are two easy ways for Mautic WordPress Integration and start tracking WordPress pages with Mautic.

  1. Using WP Mautic plugin
  2. Placing Tracking pixel in Theme or use Insert Headers and Footers Plugin.

How to run database Query on WordPress?

WordPress’s query function allows you to execute any SQL query on the WordPress database. It is best used when there is a need for specific, custom, or otherwise complex SQL queries. For more basic queries, such as selecting information from a table, see the other wpdb functions above such as get_results, get_var, get_row or get_col.
Syntax

<?php $wpdb->query('query'); ?> 

Read more from https://codex.wordpress.org/Class_Reference/wpdb#Running_General_Queries