Exceptions

exception asyncio.TimeoutError

The operation has exceeded the given deadline.

Important

This exception is different from the builtin TimeoutError exception.

exception asyncio.CancelledError

The operation has been cancelled.

This exception can be caught to perform custom operations when asyncio Tasks are cancelled. In almost all situations the exception must be re-raised.

Important

This exception is a subclass of Exception, so it can be accidentally suppressed by an overly broad try..except block:

try:
    await operation
except Exception:
    # The cancellation is broken because the *except* block
    # suppresses the CancelledError exception.
    log.log('an error has occurred')

Instead, the following pattern should be used:

try:
    await operation
except asyncio.CancelledError:
    raise
except Exception:
    log.log('an error has occurred')

exception asyncio.InvalidStateError

Invalid internal state of Task or Future.

Can be raised in situations like setting a result value for a Future object that already has a result value set.

exception asyncio.SendfileNotAvailableError

The “sendfile” syscall is not available for the given socket or file type.

A subclass of RuntimeError.

exception asyncio.IncompleteReadError

The requested read operation did not complete fully.

Raised by the asyncio stream APIs.

This exception is a subclass of EOFError.

expected

The total number (int) of expected bytes.

partial

A string of bytes read before the end of stream was reached.

exception asyncio.LimitOverrunError

Reached the buffer size limit while looking for a separator.

Raised by the asyncio stream APIs.

consumed

The total number of to be consumed bytes.