R3C6 can only be <5>

R6C7 can only be <6>

R7C4 can only be <2>

R9C1 can only be <6>

R5C4 can only be <4>

R7C2 can only be <1>

R8C4 can only be <3>

R8C8 is the only square in row 8 that can be <1>

R2C6 is the only square in column 6 that can be <1>

R1C5 can only be <3>

R2C5 can only be <2>

R6C5 can only be <1>

R4C5 can only be <9>

R5C6 can only be <2>

R1C1 is the only square in row 1 that can be <1>

R2C2 is the only square in row 2 that can be <3>

R4C3 is the only square in row 4 that can be <1>

R1C2 is the only square in column 2 that can be <6>

R2C3 is the only square in column 3 that can be <5>

R9C8 is the only square in column 8 that can be <2>

R9C2 can only be <4>

R9C5 can only be <5>

R9C9 can only be <3>

R8C5 can only be <4>

R5C8 is the only square in row 5 that can be <3>

Squares R1C8 and R1C9 in block 3 form a simple locked pair. These 2 squares both contain the 2 possibilities <57>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the block.

R2C8 - removing <7> from <46789> leaving <4689>

R2C9 - removing <7> from <678> leaving <68>

R3C8 - removing <7> from <789> leaving <89>

R1C9 is the only square in column 9 that can be <7>

R1C8 can only be <5>

Squares R6C3, R8C3, R6C2 and R8C2 form a Type-2 Unique Rectangle on <27>.

R5C2 - removing <8> from <589> leaving <59>

Squares R3C2<79>, R4C2<57> and R5C2<59> in column 2 form a comprehensive locked triplet. These 3 squares can only contain the 3 possibilities <579>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the column.

R6C2 - removing <7> from <278> leaving <28>

R8C2 - removing <7> from <278> leaving <28>

The puzzle can be reduced to a Bivalue Universal Grave (BUG) pattern, by making this reduction:

R2C8=<46>

These are called the BUG possibilities. In a BUG pattern, in each row, column and block, each unsolved possibility appears exactly twice. Such a pattern either has 0 or 2 solutions, so it cannot be part of a valid Sudoku

When a puzzle contains a BUG, and only one square in the puzzle has more than 2 possibilities, the only way to kill the BUG is to remove both of the BUG possibilities from the square, thus solving it

R2C8 - removing <46> from <4689> leaving <89>

R2C7 is the only square in row 2 that can be <4>

R4C7 can only be <5>

R4C2 can only be <7>

R8C7 can only be <9>

R5C9 can only be <8>

R5C1 can only be <9>

R2C9 can only be <6>

R6C8 can only be <7>

R6C3 can only be <2>

R4C8 can only be <4>

R8C6 can only be <6>

R7C8 can only be <6>

R8C9 can only be <5>

R3C2 can only be <9>

R5C2 can only be <5>

R2C1 can only be <7>

R6C2 can only be <8>

R8C3 can only be <7>

R7C6 can only be <9>

R8C1 can only be <8>

R2C4 can only be <8>

R2C8 can only be <9>

R3C4 can only be <7>

R3C8 can only be <8>

R8C2 can only be <2>