[BUG] Error when sending image to LMStudio with Web Browser Tool

[MarkErik]

Problem (one or two sentences)

Running into an API error when using the Web Browser Tool with Vision Capable model via LM Studio.
Getting the following error in the LM Studio logs: [Server Error] 'url' field must be a base64 encoded image

Context (who is affected and when)

Once the web browser loads the site in the Roo panel, it displays an API error, and then in the LM Studio log I can see: [Server Error] 'url' field must be a base64 encoded image

Reproduction steps

Latest version of LM Studio, latest version of MLX engine with support for Qwen3 vision models.
Have been able to reproduce this with Qwen3-VL-30b, Qwen3-VL-4b, and Gemma3-27b.

In code mode, I ask to check whether a website is rendering properly.

The browser tool activates, but then unable to do anything as it has an API error.

Expected result

No errors from API request in LM Studio log

Actual result

Error in LM Studio log: [Server Error] 'url' field must be a base64 encoded image

Variations tried (optional)

No response

App Version

3.29.0

API Provider (optional)

LM Studio

Model Used (optional)

Qwen3-VL-30b

Roo Code Task Links (optional)

No response

Relevant logs or errors (optional)

LMStudio: [Server Error] 'url' field must be a base64 encoded image

[roomote]

I'm exploring a potential fix for the LM Studio image encoding issue with the Web Browser Tool. Will investigate how images are currently being sent to LM Studio and work on ensuring they're properly base64 encoded.

[roomote]

I've opened PR #8828 to fix this issue: #8828

The fix modifies how images are sent to LM Studio by removing the data URL prefix (data:image/png;base64,) that was causing the error. LM Studio expects raw base64 encoded data only, unlike other providers.

All CI checks have passed ✅. The solution maintains backward compatibility for other providers while addressing the specific requirements of LM Studio's image handling.

Feedback welcome!

[daniel-lxs]

LMStudio doesn't like WebP and prefers PNGs