Data Management asks to delete unnecessary data, what does it mean?
This refers to leftover files from incomplete installs. Always choose Yes to delete this data, as it takes up space for no good reason. If it ever stays stuck on deleting the data in an infinite loop, you can manually delete the data yourself.
Use FTPiiU Everywhere or the FTPiiU Plugin and browse to /storage_mlc/usr/import then delete any files in the folder if any exists. This is where the partial installs exist after incomplete installs. It'll be /storage_usb/usr/import if installed to a USB.
The import folder should always be kept empty.
I put my SD card in the Wii U but it didn't give me any files. What's wrong?
Nothing is wrong. The Wii U will never give you files, because the SD card isn't used by the Wii U, which means it won't show in Data Management. You put the files on there yourself before running any exploit.
Can I install games to the SD card instead of an HDD?
No. The SD card is not used for game storage. The Wii U uses a proprietary format for drives, a format that isn't a typical format you see used(FAT32, NTFS, .etc). The SD card is primarily used for vWii(Virtual Wii mode), but also Mii Maker(for QR code creation), and Sm4sh photos.
Can I use one partition for Wii U games, and another partition for vWii games?
You cannot. The Wii U formats the entire partition. Either use a separate drive, or stick with VC injects that makes them fit all on one drive.
My HDD doesn't work or makes a weird clicking sound, what should I do?
The reason behind that is that the Wii U doesn't give enough power through one USB port to use the Hard Drive.
You can fix this by either using a powered HDD or using a Y-Cable to connect the HDD to two USB ports.
If your HDD worked for some time and then stopped working for some games/all games, it is the same issue and can be fixed with the same methods.
When extracting some of the files there are duplicates of certain ones called info.json & manifest.install, what do I do with those?
Nothing special, you can leave them there, delete them or replace them with new ones. Those files are not used in the process, therefore, won't have any impact by being or not being there.
My console suddenly lost online connectivity and I have an HDD sitting on top of the console, what should I do?
The internal antenna may have been influenced by the hard drive magnet. You can move the HDD to a different position atop the Wii U, or move it off the Wii U entirely.
Guide says to extract the contents to the root, but where is the root?
I put the extracted zip onto the root and the exploit won't work. What did I miss?
If you have environmentloader-28332a7+wiiu-nanddumper-payload-5c5ec09+fw_img_loader-c2da326 as a folder on the root, you have extracted it wrong. You have to extract the wiiu folder out of that folder to the root. That folder doesn't even belong on the SD card. Contents of the zip = wiiu folder.