Recently many users have been saying they cannot access Game Sync or Dream World due to certain issues. When attempting to access either, the user is met with Error Code 13204, an error code reserved for high traffic on the DW servers. However, the real cause of this problem was a Complete Pokedex Code made for Black and White. For whatever reason whenever this code is used it bars the user from being able to access the Dream World. Why this is no one knows at the moment. However, a fix was made recently. The following is how to fix the Error Code 13204 error:
1) Use the following code. This code completely erases your Pokedex. You will have seen 0 Pokemon and Caught 0 Pokemon.
Erase Pokedex [Select]:
2) After using the code, DO NOT attempt to access your Pokedex just yet. Since you've seen 0 Pokemon, the game will be unable to display the Pokedex correctly and will freeze if you access it at this point.
3) Go in to any tall grass and capture a Pokemon. It doesn't matter which one you capture. Just capture one.
4) After capturing a Pokemon, save your game. Once saved you should be able to access Game Sync and the Dream World without any issues.
Errors should not persist unless the Dream World is down for scheduled maintenance. In the event you continue to encounter the error, go back through and try the steps again.
DO NOT UNDER ANY CIRCUMSTANCES ATTEMPT TO USE THE COMPLETE POKEDEX CODE! Doing so at ANY point in time will result in the return of Error Code 13204. For those of you who are wondering, this is the code you should NOT use:
Complete Pokedex Code [Select]: Causes Error Code 13204
Don't Try The Following For Now
Users are reporting to be unable to tuck in pokemon after this. Customization data still transfers.
If you really want to have a complete pokedex you can test this one:
Might fix dream world tuck problem.
Credit to Alpha.
Have fun with Dream World everyone!
Major thanks to DaDeforest from GBATemp for his input on the issue as well as testing this code.
Major thanks to Kaphotics for making the fix code in question.