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Client Reference

.. currentmodule:: aiohttp


Client Session

Client session is the recommended interface for making HTTP requests.

Session encapsulates a connection pool (connector instance) and supports keepalives by default. Unless you are connecting to a large, unknown number of different servers over the lifetime of your application, it is suggested you use a single session for the lifetime of your application to benefit from connection pooling.

Usage example:

import aiohttp
import asyncio

async def fetch(client):
    async with client.get('http://python.org') as resp:
        assert resp.status == 200
        return await resp.text()

async def main():
    async with aiohttp.ClientSession() as client:
        html = await fetch(client)
        print(html)

asyncio.run(main())

The client session supports the context manager protocol for self closing.

Basic API

While we encourage :class:`ClientSession` usage we also provide simple coroutines for making HTTP requests.

Basic API is good for performing simple HTTP requests without keepaliving, cookies and complex connection stuff like properly configured SSL certification chaining.

.. function:: request(method, url, *, params=None, data=None, \
                        json=None,\
                        headers=None, cookies=None, auth=None, \
                        allow_redirects=True, max_redirects=10, \
                        encoding='utf-8', \
                        version=HttpVersion(major=1, minor=1), \
                        compress=None, chunked=None, expect100=False, raise_for_status=False, \
                        read_bufsize=None, \
                        connector=None, loop=None,\
                        read_until_eof=True, timeout=sentinel)
   :async:

   Asynchronous context manager for performing an asynchronous HTTP
   request. Returns a :class:`ClientResponse` response object. Use as
   an async context manager.

   :param str method: HTTP method

   :param url: Request URL, :class:`~yarl.URL` or :class:`str` that will
               be encoded with :class:`~yarl.URL` (see :class:`~yarl.URL`
               to skip encoding).

   :param dict params: Parameters to be sent in the query
                       string of the new request (optional)

   :param data: The data to send in the body of the request. This can be a
                :class:`FormData` object or anything that can be passed into
                :class:`FormData`, e.g. a dictionary, bytes, or file-like object.
                (optional)

   :param json: Any json compatible python object (optional). *json* and *data*
                parameters could not be used at the same time.

   :param dict headers: HTTP Headers to send with the request (optional)

   :param dict cookies: Cookies to send with the request (optional)

   :param aiohttp.BasicAuth auth: an object that represents HTTP Basic
                                  Authorization (optional)

   :param bool allow_redirects: If set to ``False``, do not follow redirects.
                                ``True`` by default (optional).

   :param aiohttp.protocol.HttpVersion version: Request HTTP version (optional)

   :param bool compress: Set to ``True`` if request has to be compressed
                         with deflate encoding.
                         ``False`` instructs aiohttp to not compress data.
                         ``None`` by default (optional).

   :param int chunked: Enables chunked transfer encoding.
                       ``None`` by default (optional).

   :param bool expect100: Expect 100-continue response from server.
                          ``False`` by default (optional).

   :param bool raise_for_status: Automatically call
                                 :meth:`ClientResponse.raise_for_status`
                                 for response if set to ``True``.  If
                                 set to ``None`` value from
                                 ``ClientSession`` will be used.
                                 ``None`` by default (optional).

      .. versionadded:: 3.4

   :param aiohttp.BaseConnector connector: BaseConnector sub-class
      instance to support connection pooling.

   :param bool read_until_eof: Read response until EOF if response
                               does not have Content-Length header.
                               ``True`` by default (optional).

   :param int read_bufsize: Size of the read buffer (:attr:`ClientResponse.content`).
                            ``None`` by default,
                            it means that the session global value is used.

      .. versionadded:: 3.7

   :param timeout: a :class:`ClientTimeout` settings structure, 300 seconds (5min)
        total timeout, 30 seconds socket connect timeout by default.

   :param loop: :ref:`event loop<asyncio-event-loop>`
                used for processing HTTP requests.
                If param is ``None``, :func:`asyncio.get_event_loop`
                is used for getting default event loop.

      .. deprecated:: 2.0

   :return ClientResponse: a :class:`client response <ClientResponse>` object.

   Usage::

      import aiohttp

      async def fetch():
          async with aiohttp.request('GET',
                  'http://python.org/') as resp:
              assert resp.status == 200
              print(await resp.text())


Connectors

Connectors are transports for aiohttp client API.

There are standard connectors:

  1. :class:`TCPConnector` for regular TCP sockets (both HTTP and HTTPS schemes supported).
  2. :class:`UnixConnector` for connecting via UNIX socket (it's used mostly for testing purposes).

All connector classes should be derived from :class:`BaseConnector`.

By default all connectors support keep-alive connections (behavior is controlled by force_close constructor's parameter).

Encapsulates single connection in connector object.

End user should never create :class:`Connection` instances manually but get it by :meth:`BaseConnector.connect` coroutine.

.. attribute:: closed

   :class:`bool` read-only property, ``True`` if connection was
   closed, released or detached.

.. attribute:: loop

   Event loop used for connection

   .. deprecated:: 3.5

.. attribute:: transport

   Connection transport

.. method:: close()

   Close connection with forcibly closing underlying socket.

.. method:: release()

   Release connection back to connector.

   Underlying socket is not closed, the connection may be reused
   later if timeout (30 seconds by default) for connection was not
   expired.

Response object

Client response returned by :meth:`aiohttp.ClientSession.request` and family.

User never creates the instance of ClientResponse class but gets it from API calls.

:class:`ClientResponse` supports async context manager protocol, e.g.:

resp = await client_session.get(url)
async with resp:
    assert resp.status == 200

After exiting from async with block response object will be released (see :meth:`release` method).

.. attribute:: version

   Response's version, :class:`~aiohttp.protocol.HttpVersion` instance.

.. attribute:: status

   HTTP status code of response (:class:`int`), e.g. ``200``.

.. attribute:: reason

   HTTP status reason of response (:class:`str`), e.g. ``"OK"``.

.. attribute:: ok

   Boolean representation of HTTP status code (:class:`bool`).
   ``True`` if ``status`` is less than ``400``; otherwise, ``False``.

.. attribute:: method

   Request's method (:class:`str`).

.. attribute:: url

   URL of request (:class:`~yarl.URL`).

.. attribute:: real_url

   Unmodified URL of request with URL fragment unstripped (:class:`~yarl.URL`).

   .. versionadded:: 3.2

.. attribute:: connection

   :class:`Connection` used for handling response.

.. attribute:: content

   Payload stream, which contains response's BODY (:class:`StreamReader`).
   It supports various reading methods depending on the expected format.
   When chunked transfer encoding is used by the server, allows retrieving
   the actual http chunks.

   Reading from the stream may raise
   :exc:`aiohttp.ClientPayloadError` if the response object is
   closed before response receives all data or in case if any
   transfer encoding related errors like malformed chunked
   encoding of broken compression data.

.. attribute:: cookies

   HTTP cookies of response (*Set-Cookie* HTTP header,
   :class:`~http.cookies.SimpleCookie`).

.. attribute:: headers

   A case-insensitive multidict proxy with HTTP headers of
   response, :class:`~multidict.CIMultiDictProxy`.

.. attribute:: raw_headers

   Unmodified HTTP headers of response as unconverted bytes, a sequence of
   ``(key, value)`` pairs.

.. attribute:: links

   Link HTTP header parsed into a :class:`~multidict.MultiDictProxy`.

   For each link, key is link param `rel` when it exists, or link url as
   :class:`str` otherwise, and value is :class:`~multidict.MultiDictProxy`
   of link params and url at key `url` as :class:`~yarl.URL` instance.

   .. versionadded:: 3.2

.. attribute:: content_type

   Read-only property with *content* part of *Content-Type* header.

   .. note::

      Returns value is ``'application/octet-stream'`` if no
      Content-Type header present in HTTP headers according to
      :rfc:`2616`. To make sure Content-Type header is not present in
      the server reply, use :attr:`headers` or :attr:`raw_headers`, e.g.
      ``'CONTENT-TYPE' not in resp.headers``.

.. attribute:: charset

   Read-only property that specifies the *encoding* for the request's BODY.

   The value is parsed from the *Content-Type* HTTP header.

   Returns :class:`str` like ``'utf-8'`` or ``None`` if no *Content-Type*
   header present in HTTP headers or it has no charset information.

.. attribute:: content_disposition

   Read-only property that specified the *Content-Disposition* HTTP header.

   Instance of :class:`ContentDisposition` or ``None`` if no *Content-Disposition*
   header present in HTTP headers.

.. attribute:: history

   A :class:`~collections.abc.Sequence` of :class:`ClientResponse`
   objects of preceding requests (earliest request first) if there were
   redirects, an empty sequence otherwise.

.. method:: close()

   Close response and underlying connection.

   For :term:`keep-alive` support see :meth:`release`.

.. method:: read()
   :async:

   Read the whole response's body as :class:`bytes`.

   Close underlying connection if data reading gets an error,
   release connection otherwise.

   Raise an :exc:`aiohttp.ClientResponseError` if the data can't
   be read.

   :return bytes: read *BODY*.

   .. seealso:: :meth:`close`, :meth:`release`.

.. method:: release()

   It is not required to call `release` on the response
   object. When the client fully receives the payload, the
   underlying connection automatically returns back to pool. If the
   payload is not fully read, the connection is closed

.. method:: raise_for_status()

   Raise an :exc:`aiohttp.ClientResponseError` if the response
   status is 400 or higher.

   Do nothing for success responses (less than 400).

.. method:: text(encoding=None)
   :async:

   Read response's body and return decoded :class:`str` using
   specified *encoding* parameter.

   If *encoding* is ``None`` content encoding is determined from the
   Content-Type header, or using the ``fallback_charset_resolver`` function.

   Close underlying connection if data reading gets an error,
   release connection otherwise.

   :param str encoding: text encoding used for *BODY* decoding, or
                        ``None`` for encoding autodetection
                        (default).


   :raises: :exc:`UnicodeDecodeError` if decoding fails. See also
            :meth:`get_encoding`.

   :return str: decoded *BODY*

.. method:: json(*, encoding=None, loads=json.loads, \
                   content_type='application/json')
   :async:

   Read response's body as *JSON*, return :class:`dict` using
   specified *encoding* and *loader*. If data is not still available
   a ``read`` call will be done.

   If response's `content-type` does not match `content_type` parameter
   :exc:`aiohttp.ContentTypeError` get raised.
   To disable content type check pass ``None`` value.

   :param str encoding: text encoding used for *BODY* decoding, or
                        ``None`` for encoding autodetection
                        (default).

                        By the standard JSON encoding should be
                        ``UTF-8`` but practice beats purity: some
                        servers return non-UTF
                        responses. Autodetection works pretty fine
                        anyway.

   :param collections.abc.Callable loads: :term:`callable` used for loading *JSON*
                          data, :func:`json.loads` by default.

   :param str content_type: specify response's content-type, if content type
      does not match raise :exc:`aiohttp.ClientResponseError`.
      To disable `content-type` check, pass ``None`` as value.
      (default: `application/json`).

   :return: *BODY* as *JSON* data parsed by *loads* parameter or
            ``None`` if *BODY* is empty or contains white-spaces only.

.. attribute:: request_info

    A :class:`typing.NamedTuple` with request URL and headers from :class:`~aiohttp.ClientRequest`
    object, :class:`aiohttp.RequestInfo` instance.

.. method:: get_encoding()

   Retrieve content encoding using ``charset`` info in ``Content-Type`` HTTP header.
   If no charset is present or the charset is not understood by Python, the
   ``fallback_charset_resolver`` function associated with the ``ClientSession`` is called.

   .. versionadded:: 3.0

ClientWebSocketResponse

To connect to a websocket server :func:`aiohttp.ws_connect` or :meth:`aiohttp.ClientSession.ws_connect` coroutines should be used, do not create an instance of class :class:`ClientWebSocketResponse` manually.

Class for handling client-side websockets.

.. attribute:: closed

   Read-only property, ``True`` if :meth:`close` has been called or
   :const:`~aiohttp.WSMsgType.CLOSE` message has been received from peer.

.. attribute:: protocol

   Websocket *subprotocol* chosen after :meth:`start` call.

   May be ``None`` if server and client protocols are
   not overlapping.

.. method:: get_extra_info(name, default=None)

   Reads optional extra information from the connection's transport.
   If no value associated with ``name`` is found, ``default`` is returned.

   See :meth:`asyncio.BaseTransport.get_extra_info`

   :param str name: The key to look up in the transport extra information.

   :param default: Default value to be used when no value for ``name`` is
                   found (default is ``None``).

.. method:: exception()

   Returns exception if any occurs or returns None.

.. method:: ping(message=b'')
   :async:

   Send :const:`~aiohttp.WSMsgType.PING` to peer.

   :param message: optional payload of *ping* message,
                   :class:`str` (converted to *UTF-8* encoded bytes)
                   or :class:`bytes`.

   .. versionchanged:: 3.0

      The method is converted into :term:`coroutine`

.. method:: pong(message=b'')
   :async:

   Send :const:`~aiohttp.WSMsgType.PONG` to peer.

   :param message: optional payload of *pong* message,
                   :class:`str` (converted to *UTF-8* encoded bytes)
                   or :class:`bytes`.

   .. versionchanged:: 3.0

      The method is converted into :term:`coroutine`

.. method:: send_str(data, compress=None)
   :async:

   Send *data* to peer as :const:`~aiohttp.WSMsgType.TEXT` message.

   :param str data: data to send.

   :param int compress: sets specific level of compression for
                        single message,
                        ``None`` for not overriding per-socket setting.

   :raise TypeError: if data is not :class:`str`

   .. versionchanged:: 3.0

      The method is converted into :term:`coroutine`,
      *compress* parameter added.

.. method:: send_bytes(data, compress=None)
   :async:

   Send *data* to peer as :const:`~aiohttp.WSMsgType.BINARY` message.

   :param data: data to send.

   :param int compress: sets specific level of compression for
                        single message,
                        ``None`` for not overriding per-socket setting.

   :raise TypeError: if data is not :class:`bytes`,
                     :class:`bytearray` or :class:`memoryview`.

   .. versionchanged:: 3.0

      The method is converted into :term:`coroutine`,
      *compress* parameter added.

.. method:: send_json(data, compress=None, *, dumps=json.dumps)
   :async:

   Send *data* to peer as JSON string.

   :param data: data to send.

   :param int compress: sets specific level of compression for
                        single message,
                        ``None`` for not overriding per-socket setting.

   :param collections.abc.Callable dumps: any :term:`callable` that accepts an object and
                          returns a JSON string
                          (:func:`json.dumps` by default).

   :raise RuntimeError: if connection is not started or closing

   :raise ValueError: if data is not serializable object

   :raise TypeError: if value returned by ``dumps(data)`` is not
                     :class:`str`

   .. versionchanged:: 3.0

      The method is converted into :term:`coroutine`,
      *compress* parameter added.

.. method:: send_frame(message, opcode, compress=None)
   :async:

   Send a :const:`~aiohttp.WSMsgType` message *message* to peer.

   This method is low-level and should be used with caution as it
   only accepts bytes which must conform to the correct message type
   for *message*.

   It is recommended to use the :meth:`send_str`, :meth:`send_bytes`
   or :meth:`send_json` methods instead of this method.

   The primary use case for this method is to send bytes that are
   have already been encoded without having to decode and
   re-encode them.

   :param bytes message: message to send.

   :param ~aiohttp.WSMsgType opcode: opcode of the message.

   :param int compress: sets specific level of compression for
                        single message,
                        ``None`` for not overriding per-socket setting.

   .. versionadded:: 3.11

.. method:: close(*, code=WSCloseCode.OK, message=b'')
   :async:

   A :ref:`coroutine<coroutine>` that initiates closing handshake by sending
   :const:`~aiohttp.WSMsgType.CLOSE` message. It waits for
   close response from server. To add a timeout to `close()` call
   just wrap the call with `asyncio.wait()` or `asyncio.wait_for()`.

   :param int code: closing code. See also :class:`~aiohttp.WSCloseCode`.

   :param message: optional payload of *close* message,
      :class:`str` (converted to *UTF-8* encoded bytes) or :class:`bytes`.

.. method:: receive()
   :async:

   A :ref:`coroutine<coroutine>` that waits upcoming *data*
   message from peer and returns it.

   The coroutine implicitly handles
   :const:`~aiohttp.WSMsgType.PING`,
   :const:`~aiohttp.WSMsgType.PONG` and
   :const:`~aiohttp.WSMsgType.CLOSE` without returning the
   message.

   It process *ping-pong game* and performs *closing handshake* internally.

   :return: :class:`~aiohttp.WSMessage`

.. method:: receive_str()
   :async:

   A :ref:`coroutine<coroutine>` that calls :meth:`receive` but
   also asserts the message type is
   :const:`~aiohttp.WSMsgType.TEXT`.

   :return str: peer's message content.

   :raise aiohttp.WSMessageTypeError: if message is not :const:`~aiohttp.WSMsgType.TEXT`.

.. method:: receive_bytes()
   :async:

   A :ref:`coroutine<coroutine>` that calls :meth:`receive` but
   also asserts the message type is
   :const:`~aiohttp.WSMsgType.BINARY`.

   :return bytes: peer's message content.

   :raise aiohttp.WSMessageTypeError: if message is not :const:`~aiohttp.WSMsgType.BINARY`.

.. method:: receive_json(*, loads=json.loads)
   :async:

   A :ref:`coroutine<coroutine>` that calls :meth:`receive_str` and loads
   the JSON string to a Python dict.

   :param collections.abc.Callable loads: any :term:`callable` that accepts
                           :class:`str` and returns :class:`dict`
                           with parsed JSON (:func:`json.loads` by
                           default).

   :return dict: loaded JSON content

   :raise TypeError: if message is :const:`~aiohttp.WSMsgType.BINARY`.
   :raise ValueError: if message is not valid JSON.

Utilities

A data class for websocket client timeout settings.

.. attribute:: ws_receive

   A timeout for websocket to receive a complete message.

   :class:`float`, ``None`` by default.

.. attribute:: ws_close

   A timeout for the websocket to close.

   :class:`float`, ``10.0`` by default.


Note

Timeouts of 5 seconds or more are rounded for scheduling on the next second boundary (an absolute time where microseconds part is zero) for the sake of performance.

E.g., assume a timeout is 10, absolute time when timeout should expire is loop.time() + 5, and it points to 12345.67 + 10 which is equal to 12355.67.

The absolute time for the timeout cancellation is 12356.

It leads to grouping all close scheduled timeout expirations to exactly the same time to reduce amount of loop wakeups.

.. versionchanged:: 3.7

   Rounding to the next seconds boundary is disabled for timeouts smaller
   than 5 seconds for the sake of easy debugging.

   In turn, tiny timeouts can lead to significant performance degradation
   on production environment.

Represents ETag identifier.

.. attribute:: value

   Value of corresponding etag without quotes.

.. attribute:: is_weak

   Flag indicates that etag is weak (has `W/` prefix).

.. versionadded:: 3.8

A data class to represent the Content-Disposition header, available as :attr:`ClientResponse.content_disposition` attribute.

.. attribute:: type

A :class:`str` instance. Value of Content-Disposition header itself, e.g. attachment.

.. attribute:: filename

A :class:`str` instance. Content filename extracted from parameters. May be None.

.. attribute:: parameters

Read-only mapping contains all parameters.

A :class:`typing.NamedTuple` with request URL and headers from :class:`~aiohttp.ClientRequest` object, available as :attr:`ClientResponse.request_info` attribute.

.. attribute:: url

   Requested *url*, :class:`yarl.URL` instance.

.. attribute:: method

   Request HTTP method like ``'GET'`` or ``'POST'``, :class:`str`.

.. attribute:: headers

   HTTP headers for request, :class:`multidict.CIMultiDict` instance.

.. attribute:: real_url

   Requested *url* with URL fragment unstripped, :class:`yarl.URL` instance.

   .. versionadded:: 3.2

HTTP basic authentication helper.

param str login:login
param str password:password
param str encoding:encoding ('latin1' by default)

Should be used for specifying authorization data in client API, e.g. auth parameter for :meth:`ClientSession.request() <aiohttp.ClientSession.request>`.

.. classmethod:: decode(auth_header, encoding='latin1')

   Decode HTTP basic authentication credentials.

   :param str auth_header:  The ``Authorization`` header to decode.
   :param str encoding: (optional) encoding ('latin1' by default)

   :return:  decoded authentication data, :class:`BasicAuth`.

.. classmethod:: from_url(url)

   Constructed credentials info from url's *user* and *password*
   parts.

   :return: credentials data, :class:`BasicAuth` or ``None`` is
             credentials are not provided.

   .. versionadded:: 2.3

.. method:: encode()

   Encode credentials into string suitable for ``Authorization``
   header etc.

   :return: encoded authentication data, :class:`str`.

Dummy cookie jar which does not store cookies but ignores them.

Could be useful e.g. for web crawlers to iterate over Internet without blowing up with saved cookies information.

To install dummy cookie jar pass it into session instance:

jar = aiohttp.DummyCookieJar()
session = aiohttp.ClientSession(cookie_jar=DummyCookieJar())

Fingerprint helper for checking SSL certificates by SHA256 digest.

param bytes digest:SHA256 digest for certificate in DER-encoded binary form (see :meth:`ssl.SSLSocket.getpeercert`).

To check fingerprint pass the object into :meth:`ClientSession.get` call, e.g.:

import hashlib

with open(path_to_cert, 'rb') as f:
    digest = hashlib.sha256(f.read()).digest()

await session.get(url, ssl=aiohttp.Fingerprint(digest))
.. versionadded:: 3.0

FormData

A :class:`FormData` object contains the form data and also handles encoding it into a body that is either multipart/form-data or application/x-www-form-urlencoded. multipart/form-data is used if at least one field is an :class:`io.IOBase` object or was added with at least one optional argument to :meth:`add_field<aiohttp.FormData.add_field>` (content_type, filename, or content_transfer_encoding). Otherwise, application/x-www-form-urlencoded is used.

:class:`FormData` instances are callable and return a :class:`aiohttp.payload.Payload` on being called.

Helper class for multipart/form-data and application/x-www-form-urlencoded body generation.

param fields:

A container for the key/value pairs of this form.

Possible types are:

If it is a :class:`tuple` or :class:`list`, it must be a valid argument for :meth:`add_fields<aiohttp.FormData.add_fields>`.

For :class:`dict`, :class:`multidict.MultiDict`, and :class:`multidict.MultiDictProxy`, the keys and values must be valid name and value arguments to :meth:`add_field<aiohttp.FormData.add_field>`, respectively.

.. method:: add_field(name, value, content_type=None, filename=None,\
                      content_transfer_encoding=None)

   Add a field to the form.

   :param str name: Name of the field

   :param value: Value of the field

                 Possible types are:

                 - :class:`str`
                 - :class:`bytes`, :class:`bytearray`, or :class:`memoryview`
                 - :class:`io.IOBase`, e.g. a file-like object

   :param str content_type: The field's content-type header (optional)

   :param str filename: The field's filename (optional)

                        If this is not set and ``value`` is a :class:`bytes`, :class:`bytearray`,
                        or :class:`memoryview` object, the `name` argument is used as the filename
                        unless ``content_transfer_encoding`` is specified.

                        If ``filename`` is not set and ``value`` is an :class:`io.IOBase`
                        object, the filename is extracted from the object if possible.

   :param str content_transfer_encoding: The field's content-transfer-encoding
                                         header (optional)

.. method:: add_fields(fields)

   Add one or more fields to the form.

   :param fields: An iterable containing:

                  - :class:`io.IOBase`, e.g. a file-like object
                  - :class:`multidict.MultiDict` or :class:`multidict.MultiDictProxy`
                  - :class:`tuple` or :class:`list` of length two, containing a name-value pair

Client exceptions

Exception hierarchy has been significantly modified in version 2.0. aiohttp defines only exceptions that covers connection handling and server response misbehaviors. For developer specific mistakes, aiohttp uses python standard exceptions like :exc:`ValueError` or :exc:`TypeError`.

Reading a response content may raise a :exc:`ClientPayloadError` exception. This exception indicates errors specific to the payload encoding. Such as invalid compressed data, malformed chunked-encoded chunks or not enough data that satisfy the content-length header.

All exceptions are available as members of aiohttp module.

.. exception:: ClientError

   Base class for all client specific exceptions.

   Derived from :exc:`Exception`


This exception can only be raised while reading the response payload if one of these errors occurs:

  1. invalid compression
  2. malformed chunked encoding
  3. not enough data that satisfy Content-Length HTTP header.

Derived from :exc:`ClientError`

.. exception:: InvalidURL

   URL used for fetching is malformed, e.g. it does not contain host
   part.

   Derived from :exc:`ClientError` and :exc:`ValueError`

   .. attribute:: url

      Invalid URL, :class:`yarl.URL` instance.

    .. attribute:: description

      Invalid URL description, :class:`str` instance or :data:`None`.

.. exception:: InvalidUrlClientError

   Base class for all errors related to client url.

   Derived from :exc:`InvalidURL`

.. exception:: RedirectClientError

   Base class for all errors related to client redirects.

   Derived from :exc:`ClientError`

.. exception:: NonHttpUrlClientError

   Base class for all errors related to non http client urls.

   Derived from :exc:`ClientError`

.. exception:: InvalidUrlRedirectClientError

   Redirect URL is malformed, e.g. it does not contain host part.

   Derived from :exc:`InvalidUrlClientError` and :exc:`RedirectClientError`

.. exception:: NonHttpUrlRedirectClientError

   Redirect URL does not contain http schema.

   Derived from :exc:`RedirectClientError` and :exc:`NonHttpUrlClientError`

Response errors

.. exception:: ClientResponseError

   These exceptions could happen after we get response from server.

   Derived from :exc:`ClientError`

   .. attribute:: request_info

      Instance of :class:`RequestInfo` object, contains information
      about request.

   .. attribute:: status

      HTTP status code of response (:class:`int`), e.g. ``400``.

   .. attribute:: message

      Message of response (:class:`str`), e.g. ``"OK"``.

   .. attribute:: headers

      Headers in response, a list of pairs.

   .. attribute:: history

      History from failed response, if available, else empty tuple.

      A :class:`tuple` of :class:`ClientResponse` objects used for
      handle redirection responses.

   .. attribute:: code

      HTTP status code of response (:class:`int`), e.g. ``400``.

      .. deprecated:: 3.1


Invalid content type.

Derived from :exc:`ClientResponseError`

.. versionadded:: 2.3

Client was redirected too many times.

Maximum number of redirects can be configured by using parameter max_redirects in :meth:`request<aiohttp.ClientSession.request>`.

Derived from :exc:`ClientResponseError`

.. versionadded:: 3.2

Web socket server response error.

Derived from :exc:`ClientResponseError`

.. exception:: WSMessageTypeError

   Received WebSocket message of unexpected type

   Derived from :exc:`TypeError`

Connection errors

These exceptions related to low-level connection problems.

Derived from :exc:`ClientError`

Derived from :exc:`ClientConnectionError` and :exc:`ConnectionResetError`

Subset of connection errors that are initiated by an :exc:`OSError` exception.

Derived from :exc:`ClientConnectionError` and :exc:`OSError`

Connector related exceptions.

Derived from :exc:`ClientOSError`

DNS resolution error.

Derived from :exc:`ClientConnectorError`

Derived from :exc:`ClientConnectorError`

Derived from :exc:`ClientConnectorError`

Response ssl error.

Derived from :exc:`ClientSSLError` and :exc:`ssl.SSLError`

Response certificate error.

Derived from :exc:`ClientSSLError` and :exc:`ssl.CertificateError`

Derived from :exc:`ClientConnectorError`

Derived from :exc:`ClientConnectionError`

Server disconnected.

Derived from :exc:`~aiohttp.ServerConnectionError`

.. attribute:: message

   Partially parsed HTTP message (optional).

Server fingerprint mismatch.

Derived from :exc:`ServerConnectionError`

Server operation timeout: read timeout, etc.

To catch all timeouts, including the total timeout, use :exc:`asyncio.TimeoutError`.

Derived from :exc:`ServerConnectionError` and :exc:`asyncio.TimeoutError`

Connection timeout on connect and sock_connect timeouts.

Derived from :exc:`ServerTimeoutError`

Reading from socket timeout on sock_read timeout.

Derived from :exc:`ServerTimeoutError`

Hierarchy of exceptions