Issue: Any attempt to unpack/unzip a Plesk backup using 7zip or WinRAR results in a compression method not supported message and the Plesk backup files and database show 0 KB.

 

Cause: As a new feature, Plesk picked up the Zstandard (zstd) compression method for backups. Current archive programs like 7zip and WinRAR don't support this compression method.

 

Resolution: There are two resolutions. One is to modify the Plesk panel.ini file to use the old/classic compression method. The second is to download and install the 7-Zip-zstd application

 

    Resolution 1: Open the panel.ini file in a file editor. The file can be located at admin/conf/panel.ini. Add these lines to the appropriate place. The [pmm] section may already exist. If so just add compressionMethod = deflate below it.

 

          [pmm]

          compressionMethod = deflate

 

    Resolution 2: Download the 7-Zip-zstd application from https://github.com/mcmilk/7-Zip-zstd/releases/tag/v22.01-v1.5.5-R3 and install it.