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Solving pyserial-asyncio blocking the event loop

· One min read
epenet

Summary of changes​

Starting in 2026.7, installation of pyserial-asyncio will be blocked in Home Assistant.

Library maintainers and custom integrations are advised to migrate to pyserial-asyncio-fast.

Background​

pyserial-asyncio blocks the event loop because it does a blocking sleep. The library is also not maintained so efforts to improve the situation haven't been released.

pyserial-asyncio-fast was created as a drop-in replacement (see the repository), and all core integrations have now been migrated.

Migration​

pyserial-asyncio-fast was designed as a drop-in replacement of pyserial-asyncio, and the necessary changes are trivial.

Requirements​

# Old
  install_requires=[
    "pyserial-asyncio"
  ]

# New
  install_requires=[
    "pyserial-asyncio-fast"
  ]

Usage​

# Old
import serial_asyncio

async def connect():
    conn = await serial_asyncio.open_serial_connection(**self.serial_settings)

# New
import serial_asyncio_fast

async def connect():
    conn = await serial_asyncio_fast.open_serial_connection(**self.serial_settings)

More examples are available in the tracking pull request.