There is no risk in moving your saved files from Wii U to Nintendo Switch. You just have to own both game versions and follow a few steps.

Here are the steps you must take to transfer the files:

  1. Turn on both Wii U and Nintendo Switch and the launch Minecraft. You can connect the Wii U on TV and have the Nintendo Switch in the handheld mode.
  2. Get in the main menu of Wii U and press ‘Play Game’, the start Minecraft.
  3. Connect to the Nintendo Network. Make sure you’re playing online so that you can successfully connect to the network. If not, you won’t be able to transfer the files, as you need that network connection.
  4. Hover over that exact file which you want to transfer and highlight it.
  5. Press ‘Save Options’ (access it by pressing ‘x’) and select ‘Transfer Save to Nintendo Switch’.
  6. Press ‘OK’ in order to confirm the transfer.
  7. Switch will take a few moments to accept that file transfer. When the screen will show ‘Transfer Save’ and tell you that it’s waiting for accepting the transfer, you’ll get to the next step.
  8. On your Nintendo Switch, in the main menu, press ‘Play Game’.
  9. Nintendo Switch must also be connected to Nintendo Network.
  10. In the ‘Load’ tab you will select ‘Transfer save from Wii U’ and press ‘Y’ to have this option selected.
  11. Confirm the save file transfer by pressing ‘OK’.
  12. Wait for the connection with the Wii U to begin.
  13. The transfer should start, wait for it to complete on both Wii U and on Nintendo Switch.
  14. Confirm on both Wii U and on the Nintendo Switch the transfer.
  15. Enter the ‘Load’ tab and load the save file which has been transferred. Once you see it, you can select and enter that saved world.