Dr. Mario World Error Codes 0003, 0007, 9001 Decoded
It's day one of Dr. Mario World's release. As with any first day, there are bound to be a few kinks to work out. While the game itself is enjoyable, if you can't access the game, well that's a problem. That's the issue many users have. Error Codes 0009, 0007, 0003, and occasionally 9001 have prevented players from getting into the game all day. Some users, like myself, didn't have these codes but did struggle with other minor bugs, such as freezing on the menu screen and just generally not loading levels.
On the plus side, my issues resolved with a software update. So if those are your problems, check for some stealth updates to your phone's operating system.
We've already covered Error Code 0009, resulting from connectivity issues, so it's best if players can wait it out as there's no clear solution, at this time.
For the others, well there's some bad news. There's nothing official, and it took some digging even to find information on them in the first place. The Dr. Mario World FAQ yielded no results, as I'm sure other players have noted already. It is only through Nintendo's main help and support page that we get anything resembling an answer.
Running on the assumption that Nintendo uses the same or similar code system for their games, we can guess what these codes mean. Here's some more bad news. Error codes 0009, 0007, and 0003 all point to internet connectivity problems. There's not much you can do here. Check your internet, reload, or try to keep your phone from sleeping.
The less common 9001 suggests an issue with a credit card or purchases with the account. It could also be a limitation caused by parental controls. Check your card or check your linked account to see if it has purchasing power or not.
All the answers relate to the Nintendo Switch or WiiU consoles, not mobile. However, it is safe to assume that Nintendo uses the same, or at least a similar, coding system for all their devices. Without an official response to these codes, this is as close to an answer as we will get. Keep checking Nintendo and social media for official answers or solutions from fellow players.