Remove deprecated feature: `ext` must start with `.` in `mimetypes.add_type` · Issue #149720 · python/cpython · GitHub

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Remove deprecated feature: ext must start with . in mimetypes.add_type #149720

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Remove deprecated feature: ext must start with . in mimetypes.add_type#149720

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stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directorytype-featureA feature request or enhancementA feature request or enhancement

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sobolevn

opened on May 12, 2026

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Feature or enhancement

See #75223

cpython/Lib/mimetypes.py

Lines 95 to 103 in f5fb491

	if ext and not ext.startswith('.'):
	from warnings import _deprecated
	_deprecated(
	"Undotted extensions",
	"Using undotted extensions is deprecated and "
	"will raise a ValueError in Python {remove}",
	remove=(3, 16),
	)

Linked PRs

• gh-149720: Remove support for undotted ext in mimetypes.MimeType.add_type #149721
• gh-149720: Fix docs for mimetypes.MimeType.add_type method #149731

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stdlibStandard Library Python modules in the Lib/ directoryStandard Library Python modules in the Lib/ directorytype-featureA feature request or enhancementA feature request or enhancement

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