Saving your game is meant to impart a feeling of relief. A sense of protection from the electronic elements hell-bent on destroying your protagonist and all the awesome they've collected on their harrowing journey of growth and fulfilment. It sucks, then, when saving goes wrong, as some players have discovered while catching 'em all in Pokémon X and Y. Fortunately, Nintendo has come to the rescue... with a map!
It's the good kind of map though, marking out exactly where you shouldn't save your game in Lumiose City. Basically, you want to avoid any area marked in blue. The page notes that saving inside a building guarantees you won't have problems.
There's mention of an incoming fix, however, no time frame provided for the impatient.
Sadly, there are a great deal of players that won't even know this map exists, so do your part for the larger Pokémon-playing community and spread the word. Put up flyers. Grab a megaphone and scream it from your local primary school. Send out mental commands using magnets and a tarpaulin made of your own hair.
OK, not that last one.