datetime.datetime.now() returns wrong time on Windows when env var TZ is set
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stdlib
type-bug
- Dominant language
- Python
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Description
Bug report
Bug description:
Europe/Berlin is UTC+2 right now, not UTC+1
Works fine on Linux OSes (builds).
C:\Users\work>python
Python 3.12.6 (tags/v3.12.6:a4a2d2b, Sep 6 2024, 20:11:23) [MSC v.1940 64 bit (AMD64)] on win32
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>>> import os
>>> os.environ['TZ'] = 'Europe/Berlin'
>>> import datetime
>>> datetime.datetime.now()
datetime.datetime(2024, 9, 20, 12, 15, 24, 771320)
>>> datetime.datetime.now(tz=datetime.UTC)
datetime.datetime(2024, 9, 20, 11, 15, 45, 162005, tzinfo=datetime.timezone.utc)
>>>
CPython versions tested on:
3.12
Operating systems tested on:
Windows
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by reproducing the reported Python 3.12 behavior on Windows with TZ set to Europe/Berlin, comparing datetime.datetime.now() with datetime.datetime.now(tz=datetime.UTC). Trace the datetime and Windows timezone handling involved; done means local time reflects the correct Berlin offset and the behavior has regression coverage.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- operating-systems
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100