fix(budget): log warning when ZoneInfo falls back to UTC

[LeeJuOh]

Relevant issues

Follow-up to #21754

Pre-Submission checklist

• I have Added testing in the tests/litellm/ directory, Adding at least 1 test is a hard requirement - see details
• My PR passes all unit tests on make test-unit
• My PR's scope is as isolated as possible, it only solves 1 specific problem
• I have requested a Greptile review by commenting @greptileai and received a Confidence Score of at least 4/5 before requesting a maintainer review

Type

🐛 Bug Fix

Changes

In #21754, the hardcoded timezone_map was replaced with ZoneInfo. On environments without the tzdata package, ZoneInfo throws an exception and silently falls back to UTC — operators have no way to tell their configured timezone is being ignored.

Rather than adding tzdata as a dependency, this PR adds a verbose_logger.warning() in the except block of _setup_timezone() to log when the fallback occurs.

• litellm/litellm_core_utils/duration_parser.py: Add warning log on timezone load failure
• No new dependencies, UTC fallback behavior preserved

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Project	Deployment	Actions	Updated (UTC)
litellm	Error		Feb 22, 2026 7:10am

[LeeJuOh]

@greptileai

[greptile-apps]

Greptile Summary

This PR adds a verbose_logger.warning() call to the _setup_timezone() function in duration_parser.py so that when ZoneInfo fails to load a configured timezone (e.g., due to a missing tzdata package or an invalid timezone string), operators are informed via a warning log rather than silently falling back to UTC.

• Added verbose_logger.warning() in the except block of _setup_timezone() with a message that includes the failed timezone string and hints at installing tzdata
• Added a corresponding unit test using unittest.mock.patch to verify the warning is logged on invalid timezone input
• No new dependencies; existing UTC fallback behavior is preserved
• Import placed at module level, consistent with project conventions

Confidence Score: 5/5

• This PR is safe to merge — it adds only a warning log line with no behavioral changes.
• The change is minimal (4 lines of production code, 6 lines of test code), well-scoped, and non-functional — it only adds observability to an existing silent fallback. The warning uses lazy % formatting (correct for logging), the import is at module level per project conventions, and the test properly mocks the logger. No risk of regression.
• No files require special attention

Important Files Changed

Filename	Overview
litellm/litellm_core_utils/duration_parser.py	Adds a verbose_logger.warning() call in the _setup_timezone() exception handler to log when timezone loading fails and falls back to UTC. Import added at module level. Minimal, well-scoped change.
tests/test_litellm/litellm_core_utils/test_duration_parser.py	Adds a mock-based test verifying that verbose_logger.warning is called when an invalid timezone triggers the UTC fallback. No real network calls; uses unittest.mock.patch.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[get_next_standardized_reset_time] --> B[_setup_timezone]
    B --> C{timezone_str is None?}
    C -->|Yes| D[Use timezone.utc]
    C -->|No| E[ZoneInfo timezone_str]
    E -->|Success| F[Return tz]
    E -->|Exception| G["verbose_logger.warning() ⬅ NEW"]
    G --> H[Fallback to timezone.utc]
    D --> I[Convert current_time to target tz]
    F --> I
    H --> I

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[LeeJuOh]

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[LeeJuOh]

@krrishdholakia Could you review this when you have a chance? This is a follow-up to #21754.