CSV Download Error Fix
The webpage at https://www.backyardgardener.com/download-csv/?pagen=1&$previousRows=0&catex=65 might be temporarily down or it may have moved permanently to a new web address.
ERR_INVALID_RESPONSE
### 1. **Check Server Logs**
– Look at the server logs to identify any PHP errors or warnings. For example:
tail -f /var/log/apache2/error.log # For Apache
tail -f /var/log/nginx/error.log # For Nginx– Common errors might include:
– Memory exhaustion.
– Missing permissions for file operations.
– Syntax or runtime errors in the script.
### 2. **Increase PHP Resource Limits**
Since your script deals with a large amount of data:
– Ensure sufficient memory and execution time limits in your `php.ini` file:
memory_limit = 512M
max_execution_time = 300– Restart your web server after changes:
sudo systemctl restart apache2
# or
sudo systemctl restart nginx### 3. **Fix Potential Script Issues**
– **Buffering Issues**: You commented out `ob_flush()` and `flush()` in your script. These help prevent memory build-up for large CSV outputs. Uncomment them:
ob_flush();
flush();– **Header Already Sent**: Ensure no output (even whitespace) is sent before the `header()` calls.
– **SQL Query Debugging**: Test `$querystr` directly in a database client (e.g., phpMyAdmin) to ensure it returns the expected results.
– **Default Values**:
Ensure the `$_GET` parameters (`pagen`, `$previousRows`, `catex`) have default values if not provided:
$pagen = intval($_GET['pagen'] ?? 1);
$previousRows = intval($_GET['$previousRows'] ?? 0);### 4. **URL Encoding**
Ensure the URL is properly encoded. For example:
https://www.backyardgardener.com/download-csv/?pagen=1&$previousRows=0&catex=65– `$previousRows` is invalid due to the `$` symbol. Rename it to something valid (e.g., `previous_rows`) in both the code and the URL.
### 5. **Testing Locally**
– Test the script locally using a tool like Postman or `curl`:
curl -O "https://www.backyardgardener.com/download-csv/?pagen=1&previousRows=0&catex=65"– Observe if any errors are logged or if the script executes without downloading a file.
### 6. **Enable Debugging**
– Add debugging in WordPress to log potential errors:
define('WP_DEBUG', true);
define('WP_DEBUG_LOG', true);
define('WP_DEBUG_DISPLAY', false);– Check the debug log in `wp-content/debug.log`.
### 7. **Handle Empty Responses**
If the `$pageposts` query returns no results:
if (empty($pageposts)) {
die('No posts found for the given criteria.');
}– Confirm there are posts in the database matching the query criteria.
### 8. **Test Headers**
Ensure headers are not sent prematurely:
– Place all `header()` calls at the very beginning, after ensuring no output occurs.
### Example Fixed Script:
<?php
/* Template Name: Download Data */
set_time_limit(0);
ini_set('output_buffering', 'off');
ini_set('zlib.output_compression', 'Off');
global $wpdb;
$catex = intval($_GET['catex'] ?? -1);
$sqlcon = ($catex !== -1) ?
"AND tt.taxonomy = 'category' AND t.term_id = '{$catex}'" :
"AND tt.taxonomy = 'category' AND t.term_id != '65'";
$querystr = "SELECT DISTINCT p.ID, p.post_title AS title, p.post_modified
FROM $wpdb->posts p
JOIN $wpdb->term_relationships tr ON (p.ID = tr.object_id)
JOIN $wpdb->term_taxonomy tt ON (tr.term_taxonomy_id = tt.term_taxonomy_id)
JOIN $wpdb->terms t ON (tt.term_id = t.term_id)
WHERE p.post_type = 'post' AND p.post_status = 'publish'
$sqlcon
ORDER BY p.post_date DESC";
$pageposts = $wpdb->get_results($querystr, OBJECT);
if (empty($pageposts)) {
header('HTTP/1.1 404 Not Found');
die('No posts found for the given criteria.');
}
header('Content-Type: text/csv; charset=utf-8');
header('Content-Disposition: attachment; filename="post_report_data.csv"');
$output = fopen('php://output', 'w');
fputcsv($output, ['Title', 'Url', 'Feature Image Url', 'Category', 'Revision Date', 'Meta Description']);
foreach ($pageposts as $post) {
$url = wp_get_attachment_url(get_post_thumbnail_id($post->ID), 'thumbnail');
$categories = implode(', ', array_map(function ($cat) {
return $cat->cat_name;
}, get_the_category($post->ID)));
fputcsv($output, [
$post->title,
get_permalink($post->ID),
$url,
$categories,
get_the_modified_date('Y-m-d H:i:s', $post->ID),
get_post_meta($post->ID, '_yoast_wpseo_metadesc', true)
]);
ob_flush();
flush();
}
fclose($output);
exit;Let me know if you encounter any specific errors during these steps.