hpack breaking changes

4.2.0

6 breaking changes, first published June 23, 2026.

• Removed
  PyPy 3.9 is no longer supported. Users on PyPy 3.9 must stay on hpack 4.1.0 or upgrade their PyPy version. github.com
• Removed
  Python 3.9 is no longer supported. Users on Python 3.9 must stay on hpack 4.1.0 or upgrade their Python version. github.com
• Behavior changed
  Variable integer decoding now rejects values larger than uint32, which previously decoded without error. Code relying on larger values will now fail. github.com
• Signature changed hpack.hpack.decode_huffman
  Was def decode_huffman(huffman_string: bytes | bytearray | None) -> bytes; now def decode_huffman(huffman_string: bytes | bytearray | memoryview | None) -> bytes. pypi.org
• Signature changed hpack.hpack.decode_integer
  Was def decode_integer(data: bytes, prefix_bits: int) -> tuple[int, int]; now def decode_integer(data: bytes | memoryview, prefix_bits: int) -> tuple[int, int]. pypi.org
• Signature changed hpack.huffman_table.decode_huffman
  Was def decode_huffman(huffman_string: bytes | bytearray | None) -> bytes; now def decode_huffman(huffman_string: bytes | bytearray | memoryview | None) -> bytes. pypi.org

Check your code

These are the changes. To see which of them reach your code, scan a public repository, or have your coding agent call check_code with your manifest or lockfile over MCP. The API reads every change in every version, not only the newest. On Team and up, a fix pull request opens for the changes that reach a connected repository. Nothing merges or deploys.