1:mod:`email.errors`: Exception and Defect classes
2-------------------------------------------------
3
4.. module:: email.errors
5   :synopsis: The exception classes used by the email package.
6
7
8The following exception classes are defined in the :mod:`email.errors` module:
9
10
11.. exception:: MessageError()
12
13   This is the base class for all exceptions that the :mod:`email` package can
14   raise.  It is derived from the standard :exc:`Exception` class and defines no
15   additional methods.
16
17
18.. exception:: MessageParseError()
19
20   This is the base class for exceptions raised by the :class:`~email.parser.Parser`
21   class.  It is derived from :exc:`MessageError`.
22
23
24.. exception:: HeaderParseError()
25
26   Raised under some error conditions when parsing the :rfc:`2822` headers of a
27   message, this class is derived from :exc:`MessageParseError`. It can be raised
28   from the :meth:`Parser.parse <email.parser.Parser.parse>` or
29   :meth:`Parser.parsestr <email.parser.Parser.parsestr>` methods.
30
31   Situations where it can be raised include finding an envelope header after the
32   first :rfc:`2822` header of the message, finding a continuation line before the
33   first :rfc:`2822` header is found, or finding a line in the headers which is
34   neither a header or a continuation line.
35
36
37.. exception:: BoundaryError()
38
39   Raised under some error conditions when parsing the :rfc:`2822` headers of a
40   message, this class is derived from :exc:`MessageParseError`. It can be raised
41   from the :meth:`Parser.parse <email.parser.Parser.parse>` or
42   :meth:`Parser.parsestr <email.parser.Parser.parsestr>` methods.
43
44   Situations where it can be raised include not being able to find the starting or
45   terminating boundary in a :mimetype:`multipart/\*` message when strict parsing
46   is used.
47
48
49.. exception:: MultipartConversionError()
50
51   Raised when a payload is added to a :class:`~email.message.Message` object
52   using :meth:`add_payload`, but the payload is already a scalar and the
53   message's :mailheader:`Content-Type` main type is not either
54   :mimetype:`multipart` or missing.  :exc:`MultipartConversionError` multiply
55   inherits from :exc:`MessageError` and the built-in :exc:`TypeError`.
56
57   Since :meth:`Message.add_payload` is deprecated, this exception is rarely
58   raised in practice.  However the exception may also be raised if the
59   :meth:`~email.message.Message.attach`
60   method is called on an instance of a class derived from
61   :class:`~email.mime.nonmultipart.MIMENonMultipart` (e.g.
62   :class:`~email.mime.image.MIMEImage`).
63
64Here's the list of the defects that the :class:`~email.parser.FeedParser`
65can find while parsing messages.  Note that the defects are added to the message
66where the problem was found, so for example, if a message nested inside a
67:mimetype:`multipart/alternative` had a malformed header, that nested message
68object would have a defect, but the containing messages would not.
69
70All defect classes are subclassed from :class:`email.errors.MessageDefect`, but
71this class is *not* an exception!
72
73.. versionadded:: 2.4
74   All the defect classes were added.
75
76* :class:`NoBoundaryInMultipartDefect` -- A message claimed to be a multipart,
77  but had no :mimetype:`boundary` parameter.
78
79* :class:`StartBoundaryNotFoundDefect` -- The start boundary claimed in the
80  :mailheader:`Content-Type` header was never found.
81
82* :class:`FirstHeaderLineIsContinuationDefect` -- The message had a continuation
83  line as its first header line.
84
85* :class:`MisplacedEnvelopeHeaderDefect` - A "Unix From" header was found in the
86  middle of a header block.
87
88* :class:`MalformedHeaderDefect` -- A header was found that was missing a colon,
89  or was otherwise malformed.
90
91* :class:`MultipartInvariantViolationDefect` -- A message claimed to be a
92  :mimetype:`multipart`, but no subparts were found.  Note that when a message
93  has this defect, its :meth:`~email.message.Message.is_multipart` method may
94  return false even though its content type claims to be :mimetype:`multipart`.
95
96