Logic Masters Deutschland e.V.

The inspiration for this one was a sudoku where you are forced to make a certain number of mistakes. Figured I'd make a 4x4 as a proof of concept. It's harder than you might expect despite the small size.

Rules:
Normal 4x4 Sudoku rules do NOT apply.

- Digits may not repeat in a column.
- Digits may not repeat in a row.
- Digits may not repeat in a box.

Error sudoku: Input the digits 1 to 4 on the grid exactly four times each. You must make exactly N total errors for each digit, where N is equal to the digit. For example, you must make exactly 3 errors with the digit 3. Only the rules marked with a dash may be violated for this purpose.

Any time a pair of digits violates any of the relevant rules, it counts as 1 error. One pair can cause multiple errors if it violates multiple rules simultaneously. For cases involving more than 2 digits, all combinations of pairs count individually.

Row/Column sums: The values outside the grid restrict the sum of the digits on that row/column.

Palindrome: The digits on the lines read the same backwards and forwards.

Links:
f-puzzles.
SudokuPad.

In case the rules are too confusing, I made a helper image as well. I recommend not referring to the helper image unless you need to, however. It might be more fun to deduce some of the combinations yourself!

Bifurcation might be tempting due to the small size, but is not necessary!