Python 3.3+Exceptionsexception

BlockingIOError

built-in exceptions

A non-blocking I/O operation would have blocked (a subclass of OSError).

Syntax

raise BlockingIOError

It never appears on its own: you only see it after putting a socket or file into non-blocking mode (socket.setblocking(False), the O_NONBLOCK flag), when no data has arrived yet or the send buffer is full — the underlying errno is EAGAIN/EWOULDBLOCK. Treat it as "try again later", not as breakage: wait for readiness with selectors or asyncio instead of spinning in a tight retry loop. After a partial write, characters_written tells you how many bytes did get through.

Examples

try:
    raise BlockingIOError
except BlockingIOError as e:
    print(type(e).__name__)   # → BlockingIOError

See also

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