Hey there, let’s work through this frustrating update issue you’re facing. I’ve helped a lot of folks troubleshoot this exact problem with Synology setups, so let’s break down the most effective fixes step by step:

1. Verify Directory Ownership & Permissions (Critical for Synology) #

Even if you’ve set file permissions to 664 and folders to 775, the user running your web server (Synology uses http by default) might not have ownership of the WordPress files. Here’s how to fix it:

• Open File Station on your Synology, navigate to your WordPress installation directory.
• Right-click the folder → Properties → Permissions tab.
• Click Add, search for and select the http user.
• Grant it Read/Write permissions, then check the box labeled Apply to this folder, sub-folders and files before saving.

2. Force WordPress to Use Direct File System Access #

By default, WordPress might try to use FTP even when direct file access is possible. Bypass this by adding a line to your wp-config.php:

• In File Station, open your WordPress root folder and edit wp-config.php.
• Add this line right above the /* That's all, stop editing! Happy publishing. */ comment:

  define('FS_METHOD', 'direct');
  

• Save the file, then try updating a plugin/theme again. This is the quickest fix for most Synology users.

3. Adjust PHP Open_Basedir Restrictions #

Synology’s Web Station often sets strict open_basedir limits that can block WordPress from accessing temporary files or writing to plugin/theme directories:

• Open Web Station → Applications → Select your WordPress site’s associated PHP profile.
• Click Edit → Go to the Core Settings tab.
• Locate the open_basedir field. Ensure it includes your WordPress directory and the system temp folder (e.g., /volume1/web/wordpress:/tmp). If it’s too restrictive, expand it or temporarily disable it (only for testing—re-enable afterward for security).

4. Clean Up Temporary & Cached Files #

Corrupted temporary download files can cause copy failures. Here’s how to clear them:

• In File Station, go to wp-content/plugins and delete any folders with .tmp in the name (these are partial plugin downloads).
• Do the same for wp-content/themes if you see temporary folders there.
• If you use a caching plugin, clear all WordPress cache before trying updates again.

5. Check Disk Space & Shared Folder Permissions #

• Make sure the Synology volume hosting your WordPress site has enough free disk space (updates need temporary storage to download and extract files).
• Double-check the Shared Folder permissions for your web directory: Go to Control Panel → Shared Folder → Select your web folder → Edit → Permissions tab, ensure the http user has Read/Write access here too.

Try these steps in order—most users fix the issue with steps 1 and 2. If you’re still stuck, you can manually upload plugins/themes via File Station to confirm the problem isn’t with WordPress itself, but the above fixes should cover 90% of cases on Synology.

内容的提问来源于stack exchange，提问作者Bryan Tilton