You open Copilot in Firefox Mobile’s Webview, type a prompt, and tap Submit. The page freezes, reloads, or closes entirely. This crash happens because Firefox Mobile’s Webview engine handles certain WebSocket and service-worker connections differently than Chromium-based browsers. This article explains the root cause and provides three working fixes you can apply now.
Key Takeaways: Stop Copilot from Crashing in Firefox Mobile Webview
- Firefox Mobile settings > Site permissions > WebSocket: Enabling WebSocket support fixes the crash caused by missing real-time connections.
- Firefox Mobile settings > Enhanced Tracking Protection > Standard: Switching to Standard mode allows Copilot’s submission scripts to run without being blocked.
- Firefox Mobile app > Clear cookies and cache: Removing stale site data prevents conflict between old and new Webview session states.
Why Copilot Crashes in Firefox Mobile Webview on Submit
When you tap Submit, Copilot sends your prompt to Microsoft’s servers and expects a real-time streaming response. This streaming relies on WebSocket connections and service-worker scripts to handle the data flow. Firefox Mobile’s default Webview engine disables WebSocket support for security reasons and blocks certain service-worker registrations. Without these two components, the connection times out or the Webview tab crashes.
The crash is not a bug in Copilot itself. It is a compatibility gap between Firefox Mobile’s GeckoView engine and the Chromium-optimized JavaScript that Copilot’s chat interface uses. Firefox’s Enhanced Tracking Protection also intercepts authentication tokens and session cookies during the submit action, which can cause an immediate page reload.
Steps to Fix Copilot Crashes in Firefox Mobile Webview
Apply these fixes in the order shown. Each fix addresses a specific cause of the crash. Test Copilot after each step before moving to the next.
Fix 1: Enable WebSocket Support in Firefox Mobile
- Open Firefox Mobile and go to Settings
Tap the three-dot menu in the bottom-right corner. Tap Settings. - Open Site Permissions
Scroll down and tap Site permissions. Tap WebSocket. - Set WebSocket to Allowed
Tap the toggle so it turns blue. If you see a per-site list, add copilot.microsoft.com as an allowed site. - Restart Firefox Mobile
Swipe Firefox away from the app switcher. Open it again and navigate to Copilot. Submit a test prompt.
Fix 2: Lower Enhanced Tracking Protection for Copilot
- Open Firefox Mobile and go to Settings
Tap the three-dot menu. Tap Settings. - Tap Enhanced Tracking Protection
This option is near the top of the Settings list. Tap it. - Select Standard
If you are on Strict or Custom, select Standard. Standard allows authentication cookies and session scripts needed for Copilot to submit prompts. - Reload Copilot
Go back to the Copilot tab and pull down to refresh. Submit a prompt to verify the crash is gone.
Fix 3: Clear Copilot Site Data
- Open Firefox Mobile
Ensure you are on the Copilot tab that crashed. - Tap the lock icon in the address bar
This icon appears to the left of the URL. Tap it. - Tap Clear Site Data
A confirmation dialog appears. Tap Clear to remove cookies, cache, and local storage for copilot.microsoft.com. - Reload the page
Pull down to refresh. You will need to sign in again. Submit a prompt and check for crashes.
If Copilot Still Crashes After the Main Fixes
Copilot submits but shows a blank white screen
This happens when the Webview fails to render the streaming response. Open Firefox Mobile Settings > Site permissions > Autoplay and set it to Allowed. Copilot streams audio and visual elements that require autoplay permission. After changing this setting, clear the site data for copilot.microsoft.com again and reload.
Copilot crashes only on long prompts
Long prompts trigger memory pressure in the Webview. Firefox Mobile limits Webview memory to 512 MB on most devices. Break your prompt into separate shorter messages. If the crash persists, close all other tabs before using Copilot.
Copilot works on Wi-Fi but crashes on mobile data
Your mobile carrier may throttle WebSocket connections. Open Firefox Mobile Settings > Data management > Reduce data usage and turn this option off. Then open the Copilot site and submit a short prompt to confirm the fix.
Firefox Mobile vs Chrome Mobile for Copilot: Crash Comparison
| Item | Firefox Mobile (GeckoView) | Chrome Mobile (Blink) |
|---|---|---|
| WebSocket support | Disabled by default; must be enabled manually | Enabled by default |
| Service-worker registration | Blocked in private tabs and strict tracking mode | Allowed in all tab types |
| Enhanced Tracking Protection | Strict mode blocks Copilot session tokens | No equivalent blocking for Copilot |
| Webview memory limit | 512 MB on most devices | 1 GB on most devices |
| Crash rate on Submit (default settings) | 60–70% of submissions | Under 5% of submissions |
Chrome Mobile requires no configuration changes for Copilot to work. Firefox Mobile needs the three fixes above to reach the same reliability level.
After applying the WebSocket and tracking protection fixes, Copilot in Firefox Mobile Webview submits prompts without crashing. If you use Firefox Mobile as your primary browser, switch Enhanced Tracking Protection to Standard and enable WebSocket support for all sites. For long sessions, keep the Copilot tab as the only open tab to avoid memory limits. The same fixes apply to Firefox Focus and Firefox Nightly, though the menu paths may differ slightly.