I am restoring a pre-WordPress-3.5 multisite into a 3.5-or-later multisite – what happened to my blogs.dir?

Before WordPress 3.5, a new WordPress Network (i.e., Multisite) installation stored media uploads (images, etc.) in the uploads directory for the “main” site on the network (site ID 1) and in a separate directory called blogs.dir for other sites. By default, blogs.dir was located at wp-content/blogs.dir, and UpdraftPlus’s multisite add-on backed it up separately.

From WordPress 3.5 onwards, a newly set up (i.e., not upgraded) multisite stores all blogs’ uploads in the uploads directory (wp-content/uploads by default). This change leads to fewer backup zips and more consistency.

When you have a backup from a pre-3.5-era multisite and wish to restore it into a 3.5-or-later multisite, you encounter an issue: you have a backup of blogs.dir, but your new site has no such directory.

This issue does not arise if you have only upgraded your pre-3.5-era multisite to 3.5 or later. In such cases, WordPress runs in a compatibility mode and retains the blogs.dir setup. Additionally, this issue is irrelevant if you are restoring a database from a pre-3.5-era multisite because WordPress’s compatibility handling will be triggered.

To address this issue, follow these steps:

1. Unzip the blogs.dir Backup Zip
   • Unzip the blogs.dir backup zip created by UpdraftPlus. It contains subdirectories for each site on the network, like blogs.dir/2, blogs.dir/3, etc.
2. Unzip the Uploads Backup Zip
   • Unzip your uploads backup zip, which contains a subdirectory named uploads.
3. Create a sites Subdirectory
   • Inside the uploads directory, create a subdirectory named sites (i.e., uploads/sites).
4. Move Contents to uploads/sites
   • Move the contents of the blogs.dir directory into uploads/sites. You will now have directories like uploads/sites/1, uploads/sites/2, etc.
5. Zip the Uploads Directory
   • Zip up the uploads directory again. Ensure the zip file has one subdirectory at the top level (uploads).
6. Import the Site Uploads
   • Use the new uploads zip to import your site uploads.

Alternatively, you can perform the restoration and then manually copy the contents from your blogs.dir backup zip into wp-content/uploads/sites on your new site.

If you need to transfer content from a post-3.5-era setup into a pre-3.5 multisite, you can reverse the above procedure.