You need a swap partition the size of your RAM, so if you installed it recently letting the installer do the partitioning you probably have a dynamic swap file and cannot hibernate. You can fix it with parted/gparted, then in fstab you need to add an argument to the line of the swap partition, but I can’t tell you anymore because I switched to Fedora. I found the info on Google anyway, probably the Mint forum.
You need a swap partition the size of your RAM, so if you installed it recently letting the installer do the partitioning you probably have a dynamic swap file and cannot hibernate. You can fix it with parted/gparted, then in fstab you need to add an argument to the line of the swap partition, but I can’t tell you anymore because I switched to Fedora. I found the info on Google anyway, probably the Mint forum.