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Resolving 'The authenticity of wordpress-X.X.X.zip could not be verified' and Update Failures

34 threads Sep 7, 2025 Core → Installing wordpress

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If you've encountered the frustrating error message 'The authenticity of wordpress-X.X.X.zip could not be verified as no signature was found' followed by an update failure, you're not alone. This common WordPress issue can stem from several underlying causes, but fortunately, most have straightforward solutions.

Why This Error Occurs

This verification error typically appears when WordPress cannot cryptographically verify the update package it has downloaded. While this might sound alarming, the downloaded file is usually legitimate. The error often masks more fundamental server-level issues that prevent the update from completing successfully.

Based on community reports, the most common underlying causes include:

  • Insufficient disk space on your hosting account
  • File permission issues that prevent WordPress from writing files
  • Server resource limitations (memory or CPU constraints)
  • Interference from hosting control panel auto-installers that manage WordPress versions
  • Outdated PHP versions that lack compatibility with newer WordPress releases

Step-by-Step Solutions

1. Check Disk Space and File Permissions

The most frequent cause of update failures is insufficient disk space. WordPress needs room to download, unpack, and replace files during an update.

To check disk space: Contact your hosting provider or check your hosting control panel to verify you have adequate space (typically at least 100MB free for updates). The error message 'fwrite(): write of 8192 bytes failed with errno=28 No space left on device' specifically indicates this issue.

To verify file permissions: Using an FTP client or file manager, ensure your WordPress directories have 755 permissions and files have 644 permissions. Incorrect permissions can prevent WordPress from creating necessary directories or copying files during updates.

2. Manual Update Method

When automatic updates fail, a manual update often succeeds:

  1. Back up your site completely - both files and database
  2. Download the latest WordPress version from the official WordPress.org website
  3. Access your server via SFTP/FTP or your hosting file manager
  4. Delete the old wp-admin and wp-includes directories
  5. Upload the new versions of these directories from the fresh download
  6. Carefully overwrite existing files in the root directory (except wp-config.php and the wp-content folder)

This method bypasses the verification process that causes the authenticity error.

3. Verify PHP Version Compatibility

WordPress updates may fail if your server is running an outdated PHP version. WordPress 6.6 requires PHP 7.4 or higher, though PHP 8.0 or newer is recommended.

To check your PHP version: Create a simple phpinfo.php file with the content <?php phpinfo(); ?> and access it through your browser. Alternatively, check your hosting control panel.

If you need to upgrade your PHP version, contact your hosting provider or use your control panel's options to switch to a supported version.

4. Address Hosting Auto-Installer Conflicts

Some hosting providers use auto-installers like Softaculous or Fantastico that may control WordPress updates. If your dashboard shows an outdated version as 'current,' you may need to:

  • Update through your hosting control panel instead of the WordPress dashboard
  • Or manually update as described above, bypassing the auto-installer entirely

5. Temporarily Disable Verification (Advanced)

For those comfortable with code modifications, you can add this line to your wp-config.php file to temporarily disable the verification check:

define('WP_VERIFY_UPDATE_SIGNATURE', false);

Note: This should only be used as a temporary measure and removed after successfully updating, as it reduces security during the update process.

When to Contact Your Hosting Provider

If none of these solutions work, the issue may be with your hosting environment. Contact your hosting support with details of the error message and the steps you've already tried. They can check for:

  • Server-level restrictions on file operations
  • Resource limitations (memory, processes, or inodes)
  • Special configurations that might interfere with WordPress updates

Preventing Future Update Issues

To minimize update problems going forward:

  • Maintain at least 500MB of free disk space
  • Keep your PHP version updated (currently PHP 8.1 or 8.2 recommended)
  • Perform regular backups before updating
  • Consider using a staging environment for testing major updates

While the 'authenticity could not be verified' error can be frustrating, it's typically resolvable through these methods. The WordPress community continues to share solutions and workarounds for these common update challenges.

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