NumPy 2.5.3 Release Notes

The NumPy 2.5.3 is a patch release that fixes bugs discovered after the 2.5.2
release. Apart from the usual bug and maintenance work, there are a number of
StringDType related fixes for problems discovered during the ongoing string
work in the main branch.

This release supports Python versions 3.12-3.15

Changes

• Casting a fixed-width byte string array (np.bytes_) to StringDType
  now raises TypeError when the bytes are not valid UTF-8. Previously the
  invalid bytes were stored as-is and later caused undefined behavior in
  string operations.

  (gh-32296)

• MaskedArray._fill_value would become stale when ufuncs that change dtype
  left the result holding a fill_value typed for the old dtype. The mismatch
  was silent until something later called _check_fill_value, such as
  .view(), and then a TypeError would be raised. Now, when the copied
  fill_value is no longer valid for the new dtype, fall back to the
  default fill_value for that dtype instead of propagating the stale value.
  This may raise a ComplexWarning if the fill_value is complex and the
  new dtype is real.

  (gh-32423)

Contributors

A total of 9 people contributed to this release. People with a "+" by their
names contributed a patch for the first time.

• Charles Harris
• Iason Krommydas
• James Davies +
• Joren Hammudoglu
• Maanas Arora
• Matti Picus
• Nathan Goldbaum
• Shikhar Goel +
• Yeonho Kim +

Pull requests merged

A total of 27 pull requests were merged for this release.

• #32235: MAINT: Prepare 2.5.x for further development
• #32289: BUG: raise ValueError when reading into record array with references...
• #32290: BUG: avoid uninitialized memory access / NULL-pointer deref in...
• #32291: TYP: fix np.random.{get,set}_bit_generator implicit re-exports...
• #32292: BUG: don't assume strides are a multiple of itemsize in stringdtype...
• #32293: CI: fix ccache CC override, add CXX in mac Conda CI (#32285)
• #32303: BUG: Fix ref leak in [convert_from_type]{#convert_from_type} for custom scalar types...
• #32304: BUG: fix a number of issues around iterators and StringDType...
• #32326: TST: avoid allocating huge tuple of arrays in concatenate test...
• #32338: BUG: avoid possible UB in 'safe' multiplication helpers (#32294)
• #32339: MAINT: use PyObject_ functions instead of raw PyArray_ ones (#32331)
• #32378: BUG: validate UTF-8 and harden StringDType bounds handling (#32296)
• #32380: BUG: fix two error handling mistakes in stringdtype replace loop...
• #32381: BUG: fix visibility annotations for functions in StringDType...
• #32384: MAINT: Update ml_dtypes pin to 8/21/2026.
• #32385: MAINT: Update numpy/_core/src/umath/svml
• #32410: MAINT: skip failing cython limited API tests on Cython 3.3.0...
• #32427: BUG: close duplicated file descriptor if fdopen fails (#32386)
• #32428: MAINT: add missing space in warning and error messages (#32405)
• #32430: BUG: fix error handling in StringDType to fixed-width bytes case...
• #32441: MAINT: Only run nightly BLAS tests on main.
• #32471: BUG: fix memory leak in StringDType creation error path (#32470)
• #32477: BUG: fix stale fill_value after ufuncs change MaskedArray dtype...
• #32478: MAINT: exit deadlock tests quickly on slow hardware (#32466)
• #32481: BUG: Backport StringDType byteorder fixes
• #32506: DOC: use static scipy doc site for intershpinx (#32503)
• #32509: BUG: fix crash in ufunc.resolve_dtypes with a Python scalar type...