If you have noticed your C drive losing several gigabytes of storage without explanation, Google Chrome is likely responsible. The browser has been quietly downloading a roughly 4GB file called weights.bin onto users computers without asking for permission, and most people only find out when they go hunting for what is eating their disk space.
The file lives inside a folder named OptGuideOnDeviceModel, buried deep inside Chrome’s user data directory. It contains the weights for Gemini Nano, Google’s on-device large language model, and Chrome installs it automatically on devices that meet the minimum hardware requirements. There is no checkbox in Chrome settings labeled “download a 4GB AI model.” The browser simply does it in the background.
The issue went viral in February 2026 after user @zephyrianna posted on X about finding the file on her Windows C drive. The post racked up over 700,000 views and triggered a wave of outrage across developer forums and tech communities, though reports of the behavior in community forums date back more than a year before it went mainstream.
What is this file and why is Chrome downloading it?
Gemini Nano is Google’s smallest locally-running AI model. It performs computations directly on the user’s device rather than sending data to Google’s servers, and Chrome uses it to power several built-in features including “Help me write,” on-device scam detection, tab organization, and page summarization. Google has marketed these as privacy-friendly features, since the data theoretically never leaves the machine.
The file is located at %LOCALAPPDATA%\Google\Chrome\User Data\OptGuideOnDeviceModel on Windows machines. The download triggers automatically when Chrome’s AI features are active, which they are by default in recent versions of the browser.
The privacy argument, however, has a significant flaw. Forensic evidence published by privacy researcher and computer scientist Alexander Hanff shows that the “Help me write” feature actually routes user queries to Google’s cloud servers regardless of the local model sitting on the disk.
Users are paying the storage and bandwidth cost without receiving the privacy benefit Google implies. A commenter on Hacker News put it plainly: “Everything gets sent to the cloud anyway so the local LLM seems mostly to exist as a disguise for that.”
Google also chose an obscure name for the folder. A user checking their disk usage would have no way of connecting OptGuideOnDeviceModel/weights.bin to Gemini Nano. Critics point out that a more honest name would be something like GeminiNanoLLM/weights.bin.
The legal problem and how to actually remove it
What makes the situation worse is that deleting the file does not solve anything. Chrome automatically re-downloads it the next time the browser launches. There is no opt-in prompt, no opt-out toggle in the standard settings, and no notification that the download happened at all.
A 4GB file downloading silently can cause disk overflow and slow down system performance, particularly on machines with smaller SSDs or limited storage. For users on metered internet connections, it also consumes data they did not agree to spend.
Hanff, who documented the issue in detail on his blog That Privacy Guy, argues the installation likely breaches the ePrivacy Directive Article 5(3), GDPR Articles 5(1) and 25, and potentially California’s CCPA. If EU regulators pursue the matter, Google could face fines of up to 4% of global revenue, which based on 2025 financials amounts to roughly €11 billion.
Chrome’s component updater system is designed to push security patches and small browser components silently, which is standard and expected behavior. A 4GB AI model is a different matter entirely, and users discovering it are doing so by checking disk usage or browsing their file system, not because Chrome told them anything.
To permanently stop Chrome from downloading the model, the most reliable method is a Windows Registry policy. Unlike disabling flags in chrome://flags, which Chrome can reset on updates, a Registry policy cannot be overridden by the browser’s own update logic.
To apply it, open the Registry Editor by searching for regedit in the Start menu. Navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Policies. Right-click Policies, select New, then Key, and name it Google. Right-click the Google key, select New, then Key, and name it Chrome. Right-click inside the Chrome folder, select New, then DWORD (32-bit) Value, and name it GenAILocalFoundationalModelSettings. Double-click it, set the value to 1, click OK, and restart your computer. Once applied, Chrome will stop downloading Gemini Nano and will delete any existing model already on the disk.
For users comfortable with Command Prompt, the same result can be achieved by running the following lines as Administrator:
reg add “HKLM\SOFTWARE\Policies\Google\Chrome” /f reg add “HKLM\SOFTWARE\Policies\Google\Chrome” /v GenAILocalFoundationalModelSettings /t REG_DWORD /d 1 /f reg add “HKLM\SOFTWARE\Policies\Google\Chrome” /v AIModeSettings /t REG_DWORD /d 1 /f reg add “HKLM\SOFTWARE\Policies\Google\Chrome” /v GeminiSettings /t REG_DWORD /d 1 /f reg add “HKLM\SOFTWARE\Policies\Google\Chrome” /v HelpMeWriteSettings /t REG_DWORD /d 2 /f reg add “HKLM\SOFTWARE\Policies\Google\Chrome” /v TabOrganizerSettings /t REG_DWORD /d 2 /f
Important: back up the Registry before making changes. Open Registry Editor, go to File, then Export, and save a copy somewhere safe. Incorrect edits can cause system instability.
After applying the policy, only the AI features that depend on the local model will stop working. Cloud-based features like AI Mode and Gemini in the side panel will continue to function normally.
Users of Firefox, Brave, and Edge are not affected by this issue at all, as the behavior is exclusive to standard Chrome builds.
It is also worth noting that Gemini Nano powers on-device scam detection in addition to user-facing AI tools. This means the model may attempt to download even on machines where the user has never interacted with any AI feature in Chrome.
Chrome 148, which hit stable release today, includes the Prompt API, which allows webpages to trigger Gemini Nano model downloads via JavaScript. That means the download could eventually be initiated by individual websites, not just the browser itself.
Hanff closed his blog post with a direct challenge to Google. All the company had to do, he wrote, was ask: “Chrome would like to download a 4GB AI model file to your device to power the following features. Allow, or skip and decide later.” One prompt. That is all it would have taken.
What do you think, is Google out of line for doing this without asking, or is this just the price of having AI built into your browser? Tell us in the comments!