BackWPup and PHP 8: Understanding Compatibility, Warnings, and Solutions

Upgrading your server's PHP version is a critical step for security and performance. However, for users of the BackWPup plugin, this process can raise important questions about compatibility. Based on community discussions and common issues, this guide explains what to expect when running BackWPup on PHP 8.0 and 8.1.

Is BackWPup Compatible with PHP 8?

The short answer is yes. Numerous users have reported successfully running BackWPup on PHP 8.0, 8.1, and even 8.2. The core functionality of creating and restoring backups generally continues to work. However, the experience is not always seamless, and you will likely encounter some warnings.

Common Issues and What They Mean

When you upgrade, you might see two main types of problems:

1. Deprecation Warnings: The most common issue is a flood of deprecation notices in your logs. These are primarily related to the removed `mcrypt` encryption extension. An analysis with a PHP compatibility checker will show many errors in the file inc/class-encryption-mcrypt.php. While these warnings look alarming, they are often non-fatal. The plugin falls back to other methods, and the backup job may still complete successfully.
2. "Job has started, but not responded for 10 seconds": Some users have encountered this error after a PHP upgrade. This is often related to the server environment and missing PHP extensions rather than a direct incompatibility with PHP 8 itself. The 'Server self connect' test in the plugin's settings may also show an "Not expected HTTP response" error, even with a 200 status code.

Troubleshooting Steps and Solutions

1. For Deprecation Warnings

These warnings are a known issue and are expected to be fully resolved in a future major update (version 4.0) from the BackWPup team. Until that update is publicly released, you have a few options:

• Ignore the Warnings (If Backups Work): If your backups are completing successfully, you can often safely ignore these deprecation notices. They are warnings, not critical errors.
• Configure Error Reporting: Adjust your site's wp-config.php to not display deprecation warnings on your live site. You can change WP_DEBUG_DISPLAY to false. However, always ensure errors are still being logged.

2. For the "Not Responding" Error

If your backup jobs are failing to start, the issue is likely your server configuration under PHP 8.

• Check PHP Extensions: Ensure all necessary PHP extensions are installed and enabled for PHP 8. Key extensions often include curl, openssl, zip, and mbstring. The absence of extensions like xmlrpc has been noted in environments where this error occurs.
• Clear Caches: In at least one case, a user resolved a plugin conflict error (specifically with All in One SEO) simply by clearing the server's PHP cache. It's a quick and easy step worth trying.
• Verify Server Self-Connect: The error in the 'Server self connect' test suggests a problem with the server's loopback connectivity. Contact your hosting provider and ask them to verify that local HTTP requests (from your server to itself) are functioning correctly under the new PHP version.

Conclusion and Outlook

BackWPup is functionally compatible with PHP 8.x, but it displays numerous deprecation warnings due to outdated code. The development team has acknowledged these issues and has been working on a version 4.0 update to provide full compatibility.

For now, if your backups are working, you can proceed with PHP 8 while ignoring the logs. If your jobs are failing, focus your troubleshooting on your server's PHP extension setup and configuration. As always, before any major PHP upgrade, test thoroughly on a staging site first and ensure you have a recent, verified backup.