Comment 19 for bug 405022

Diego, are you able to create new partitions with the FAT32 file system, and then resize these new partitions?

This answer would help to diagnose if the problem occurs for all FAT32 file systems on your disk device, or one specific file system.

As a side note, GParted uses the libparted library to resize FAT16, FAT32, HFS, and HFS+ file systems. This library has not seen much development work in the last while. The Parted (not GParted) team is focusing on partition editing operations only, and plans to deprecate many of the file system specific commands.