:mod:`!email.errors`: Exception and Defect classes
--------------------------------------------------
.. module:: email.errors
:synopsis: The exception classes used by the email package.
**Source code:** :source:`Lib/email/errors.py`
--------------
The following exception classes are defined in the :mod:`email.errors` module:
.. exception:: MessageError()
This is the base class for all exceptions that the :mod:`email` package can
raise. It is derived from the standard :exc:`Exception` class and defines no
additional methods.
.. exception:: MessageParseError()
This is the base class for exceptions raised by the
:class:`~email.parser.Parser` class. It is derived from
:exc:`MessageError`. This class is also used internally by the parser used
by :mod:`~email.headerregistry`.
.. exception:: HeaderParseError()
Raised under some error conditions when parsing the :rfc:`5322` headers of a
message, this class is derived from :exc:`MessageParseError`. The
:meth:`~email.message.EmailMessage.set_boundary` method will raise this
error if the content type is unknown when the method is called.
:class:`~email.header.Header` may raise this error for certain base64
decoding errors, and when an attempt is made to create a header that appears
to contain an embedded header (that is, there is what is supposed to be a
continuation line that has no leading whitespace and looks like a header).
.. exception:: BoundaryError()
Deprecated and no longer used.
.. exception:: MultipartConversionError()
Raised when a payload is added to a :class:`~email.message.Message` object
using :meth:`add_payload`, but the payload is already a scalar and the
message's :mailheader:`Content-Type` main type is not either
:mimetype:`multipart` or missing. :exc:`MultipartConversionError` multiply
inherits from :exc:`MessageError` and the built-in :exc:`TypeError`.
Since :meth:`Message.add_payload` is deprecated, this exception is rarely
raised in practice. However the exception may also be raised if the
:meth:`~email.message.Message.attach`
method is called on an instance of a class derived from
:class:`~email.mime.nonmultipart.MIMENonMultipart` (e.g.
:class:`~email.mime.image.MIMEImage`).
.. exception:: HeaderWriteError()
Raised when an error occurs when the :mod:`~email.generator` outputs
headers.
.. exception:: MessageDefect()
This is the base class for all defects found when parsing email messages.
It is derived from :exc:`ValueError`.
.. exception:: HeaderDefect()
This is the base class for all defects found when parsing email headers.
It is derived from :exc:`MessageDefect`.
Here is the list of the defects that the :class:`~email.parser.FeedParser`
can find while parsing messages. Note that the defects are added to the message
where the problem was found, so for example, if a message nested inside a
:mimetype:`multipart/alternative` had a malformed header, that nested message
object would have a defect, but the containing messages would not.
All defect classes are subclassed from :class:`email.errors.MessageDefect`.
* :class:`NoBoundaryInMultipartDefect` -- A message claimed to be a multipart,
but had no :mimetype:`boundary` parameter.
* :class:`StartBoundaryNotFoundDefect` -- The start boundary claimed in the
:mailheader:`Content-Type` header was never found.
* :class:`CloseBoundaryNotFoundDefect` -- A start boundary was found, but
no corresponding close boundary was ever found.
.. versionadded:: 3.3
* :class:`FirstHeaderLineIsContinuationDefect` -- The message had a continuation
line as its first header line.
* :class:`MisplacedEnvelopeHeaderDefect` - A "Unix From" header was found in the
middle of a header block.
* :class:`MissingHeaderBodySeparatorDefect` - A line was found while parsing
headers that had no leading white space but contained no ':'. Parsing
continues assuming that the line represents the first line of the body.
.. versionadded:: 3.3
* :class:`MalformedHeaderDefect` -- A header was found that was missing a colon,
or was otherwise malformed.
.. deprecated:: 3.3
This defect has not been used for several Python versions.
* :class:`MultipartInvariantViolationDefect` -- A message claimed to be a
:mimetype:`multipart`, but no subparts were found. Note that when a message
has this defect, its :meth:`~email.message.Message.is_multipart` method may
return ``False`` even though its content type claims to be :mimetype:`multipart`.
* :class:`InvalidBase64PaddingDefect` -- When decoding a block of base64
encoded bytes, the padding was not correct. Enough padding is added to
perform the decode, but the resulting decoded bytes may be invalid.
* :class:`InvalidBase64CharactersDefect` -- When decoding a block of base64
encoded bytes, characters outside the base64 alphabet were encountered.
The characters are ignored, but the resulting decoded bytes may be invalid.
* :class:`InvalidBase64LengthDefect` -- When decoding a block of base64 encoded
bytes, the number of non-padding base64 characters was invalid (1 more than
a multiple of 4). The encoded block was kept as-is.
* :class:`InvalidDateDefect` -- When decoding an invalid or unparsable date field.
The original value is kept as-is.
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