Table of Contents
Problem Description #
After installing or updating the Wishlist plugin, the admin area (or site) breaks. WP shows a fatal error like Uncaught Error: Class “WP_Background_Process” not found, preventing access to plugin settings, plugin list, or sometimes the entire admin dashboard.
Common symptoms
- White screen or “Critical error on this website” message in WP admin. WordPress.org+1
- Error trace referencing: includes/free/class-alg-wc-wish-list-stock-bkg-process.php and “WP_Background_Process”. WordPress.org
Cause
- The plugin tries to load a background‑process class that’s missing — likely due to incomplete file deployment or conflict with another plugin/theme that interferes with autoloading. WordPress.org+1
Solution (step‑by‑step)
- Temporarily disable the plugin — via FTP or hosting file manager, rename the plugin folder wish-list-for-woocommerce to something like wish-list-for-woocommerce-disabled. This restores access to WP admin.
- Ensure plugin is fully uploaded / no missing files — re-download the plugin ZIP from WordPress.org and re-upload via WP Admin → Plugins → Add New → Upload. This ensures all files (including background‑process classes) are present.
- Check for conflicts: disable other plugins or custom code that modify autoloaders or background processes; switch to a default theme. Then reactivate the wishlist plugin and test.
- Verify PHP version: make sure your server uses a PHP version supported by the plugin (per plugin page requirements). WordPress.org+1
- If error persists, contact support: Provide the full error message, WordPress version, PHP version, theme name, and list of active plugins, this helps developers debug missing file / dependency issues.
Prerequisites
- FTP or hosting access to rename/delete plugin folder.
- Backup of site before making changes.
Additional Notes
- This issue seems rare but critical, treat it as high-priority if it arises.
- Always test plugin updates on a staging site before applying to production.
Related Issues / Alternative Solutions
- Consider waiting for a patched release if this is due to a plugin bug, check changelog.
- If background processing isn’t essential for your store (e.g. stock alerts), consider disabling related features temporarily for stability.
