fix(embedding): omit null encoding_format for openai requests

[meutsabdahal]

Relevant issues

Fixes #25388

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Type

🐛 Bug Fix
✅ Test

Changes

• Stop sending encoding_format: null in embedding requests when it is not set.
• Preserve explicit encoding_format values (for example, "float").
• Add regression tests for both behaviors (unset omitted, explicit preserved).

[vercel]

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Project	Deployment	Actions	Updated (UTC)
litellm	Ready	Preview, Comment	Apr 9, 2026 4:20am

[codspeed-hq]

Merging this PR will not alter performance

✅ 16 untouched benchmarks

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_{Comparing meutsabdahal:fix/25388-embedding-encoding-format (91e7570) with main (6e6f5be)}

[greptile-apps]

Greptile Summary

This PR fixes a bug where encoding_format: null was being sent to OpenAI-compatible embedding APIs when the parameter was not explicitly provided, by removing the else branch that set optional_params["encoding_format"] = None. Two regression tests are added that mock openai_chat_completions.embedding to verify the parameter is absent when unset and present when explicitly supplied.

Confidence Score: 5/5

Safe to merge — minimal, targeted fix with proper regression coverage.

The change is a 3-line removal that corrects a clearly wrong default (sending null to an API that doesn't expect it). Tests are mock-based (no real network calls), cover both the unset and explicit cases, and live in the correct test directory. No other concerns were identified.

No files require special attention.

Vulnerabilities

No security concerns identified.

Important Files Changed

Filename	Overview
litellm/main.py	Removes 3-line else block that was explicitly setting optional_params["encoding_format"] = None when no encoding format was provided, preventing null values from being forwarded to OpenAI-compatible APIs.
tests/test_litellm/llms/openai/embeddings/test_openai_embeddings_encoding_format.py	New test file with two mock-based regression tests: one verifying encoding_format is absent from optional_params when unset, another verifying the explicit value is forwarded correctly.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A["litellm.embedding(...)"] --> B["get_optional_params_embeddings(encoding_format=...)"]
    B --> C{"encoding_format\nprovided?"}
    C -- "Yes (e.g. 'float')" --> D["optional_params includes\nencoding_format='float'"]
    C -- "No (None)" --> E["optional_params does NOT\ninclude encoding_format"]
    D --> F["openai_chat_completions.embedding(optional_params=...)"]
    E --> F
    F --> G["OpenAI SDK sends request\nwithout null encoding_format"]

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_{Reviews (1): Last reviewed commit: "fix(embedding): omit null encoding_forma..." | Re-trigger Greptile}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[meutsabdahal]

@yuneng-berri @ishaan-jaff @Sameerlite @krrish-berri-2

Hey! Could you please take a look at this PR when you get a chance? I’d really appreciate your feedback. Thanks!