Sourced from multidict's releases.

7.1.0 is a correctness and housekeeping release. It changes what keys() yields, fixes a long list of crashes and inconsistencies that Python code run in the middle of an operation could trigger, stores the common all-str multidicts in half the space, and deprecates multidict.upstr.

Behaviour changes. keys() and iteration over a multidict yield each key once, as spelled in its first item, so len(d.keys()) counts distinct keys; items(), values() and len(d) still see every item. A str subclass's own lower() is no longer called to compute the case-insensitive identity of a CIMultiDict key.

Robustness. Finalizers, __eq__(), __repr__(), lower() and argument iterators that read or mutate the multidict in the middle of __init__(), update(), merge(), del d[key], popall(), popitem(), to_dict() or repr() no longer crash the C extension, lose or duplicate pairs, or make the two backends disagree. Two data races against lock-free readers on the free-threaded build are gone too.

Memory. A MultiDict whose keys are all exact str, and a CIMultiDict whose keys are all exact istr, are stored in a compact table without a separate identity and hash per entry, which cuts their size by about 45%.

Bug fixes

• Fixed building the C extension on platforms where char is unsigned, such as ARM, PowerPC, s390x and RISC-V, and with GCC 9, which flags CPython's own headers from 3.12 on; both failed on a sign conversion warning since -Wconversion took effect. GCC 9 builds the extension without -Wconversion -- by @​asvetlov.

  Related issues and pull requests on GitHub: #1759, #1760.

• Fixed getversion() returning only the low 32 bits of the version on Windows and on 32-bit platforms, where two different versions could compare equal, and fixed a race in the pure-Python implementation on GIL builds that could give two multidicts mutated at the same time from different threads the same version -- by @​asvetlov.

  Related issues and pull requests on GitHub: #1607, #1610.

... (truncated)

Sourced from multidict's changelog.

7.1.0

(2026-10-08)

7.1.0 is a correctness and housekeeping release. It changes what :meth:~multidict.MultiDict.keys yields, fixes a long list of crashes and inconsistencies that Python code run in the middle of an operation could trigger, stores the common all-:class:str multidicts in half the space, and deprecates multidict.upstr.

Behaviour changes. :meth:~multidict.MultiDict.keys and iteration over a multidict yield each key once, as spelled in its first item, so len(d.keys()) counts distinct keys; :meth:~multidict.MultiDict.items, :meth:~multidict.MultiDict.values and len(d) still see every item. A :class:str subclass's own lower() is no longer called to compute the case-insensitive identity of a :class:~multidict.CIMultiDict key.

Robustness. Finalizers, __eq__(), __repr__(), lower() and argument iterators that read or mutate the multidict in the middle of __init__(), update(), merge(), del d[key], :meth:~multidict.MultiDict.popall, :meth:~multidict.MultiDict.popitem, :meth:~multidict.MultiDict.to_dict or :func:repr no longer crash the C extension, lose or duplicate pairs, or make the two backends disagree. Two data races against lock-free readers on the free-threaded build are gone too.

Memory. A :class:~multidict.MultiDict whose keys are all exact :class:str, and a :class:~multidict.CIMultiDict whose keys are all exact :class:~multidict.istr, are stored in a compact table without a separate identity and hash per entry, which cuts their size by about 45%.

Bug fixes

• Fixed building the C extension on platforms where char is unsigned, such as ARM, PowerPC, s390x and RISC-V, and with GCC 9, which flags CPython's own headers from 3.12 on; both failed on a sign conversion warning since -Wconversion took effect. GCC 9 builds the extension without -Wconversion -- by :user:asvetlov.

  Related issues and pull requests on GitHub: :issue:1759, :issue:1760.

• Fixed :func:~multidict.getversion returning only the low 32 bits of the version on Windows and on 32-bit platforms, where two different versions could compare equal, and fixed a race in the pure-Python implementation on GIL builds that could give two multidicts mutated at the same time from different threads the same version

... (truncated)

• 709f260 Trim the test run of the emulated wheel jobs (#1762)
• dbc3aba Build(deps): Bump pypa/cibuildwheel from 4.2.1 to 4.3.0 (#1761)
• ef68371 Build without -Wconversion on GCC 9 (#1760)
• e812c4f Fix the C extension build where char is unsigned (#1759)
• f9459a1 Release 7.1.0 (#1758)
• 45552bd Fold the hash chain walk into _md_update() (#1757)
• 84c5412 Move to_dict() into to_dict.h and mark only later duplicates (#1756)
• cfd8ea2 Reserve room for update() and merge() only when keys are added (#1755)
• fb828e3 Prefix header-local helpers with an underscore (#1753)
• 3c3fc84 Move istr_canonical() into istr_object.h (#1754)
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