Gemma 4 support: model_type `gemma4` not recognized

[2imi9]

Summary

Google released the Gemma 4 model family (gemma-4-E2B-it, gemma-4-E4B-it) which introduces a new model_type: gemma4. This model type was added in transformers >= 5.5.0, but vLLM currently ships with an older version.

Error

The checkpoint you are trying to load has model type `gemma4` but Transformers does not recognize this architecture.

Steps to reproduce

vllm serve 2imi9/gemma-4-E2B-it-NVFP4A16

Or with any Gemma 4 model (e.g. google/gemma-4-E2B-it, google/gemma-4-E4B-it).

Key details

• Gemma 4 is a multimodal model (vision + audio + text) using AutoModelForImageTextToText
• Architecture includes vision_tower, audio_tower, embed_vision, embed_audio modules
• Requires transformers >= 5.5.0 for gemma4 model type registration

Related

• Gemma 4 support requires transformers >= 5.5.0 (currently pinned <= 4.57.6) llm-compressor#2562 — same transformers version issue in llm-compressor
• [Examples] Add Gemma 4 E4B NVFP4A16 quantization example llm-compressor#2561 — Gemma 4 NVFP4A16 quantization example