When applying writebacks from a Machine, an error message indicating "Keeping writeback for an old snapshot is not allowed" appears, making it impossible to keep writebacks for that Machine.
All progress on the snapshot in question will be lost, so any updates or changes will need to be performed again.
1. Turn off the Machine in question.
2. Ensure "Keep Writebacks" is turned off for that Machine. (See ggRock Machines Administration Manual for more information)
3. From the "Images" tab, click on each image associated with the Machine in question (system image and games image) and perform one of the two below tasks:
Option 1: Activate the newest snapshot and apply writebacks to that image.
Option 2: Delete the newest snapshot, keeping in mind that deleting the newest snapshot will discard any recently made changes that have not been committed.
When this error is encountered it means the Machine you are trying to apply the writebacks for is currently on an old snapshot (e.g. writebacks have been kept for this system, but you have applied writebacks from another system in the meantime, making it out of sync with the rest of your Machines).