Troubleshooting
Most Lumetrope problems come from the system webview, browser security rules or a busy local port. Find your symptom below.
| Problem | Fix |
|---|---|
| Linux: blank or white window (often NVIDIA) | Start with WEBKIT_DISABLE_DMABUF_RENDERER=1 lumetrope-desktop. |
| Linux: WebAssembly "simd" error | WebKitGTK is older than 2.40. Update webkit2gtk-4.1. |
| Blur or luma mattes look wrong | Older webview. Lumetrope falls back to the CPU renderer; switch with View, Renderer. |
| WebM export disabled | Your webview lacks a WebCodecs encoder, or the page is not https. GIF and WebP always work. |
| Save downloads a file instead of writing back | Needs https and Chrome or Edge, or the desktop app. |
| macOS: app will not open | See Install on macOS for the Gatekeeper fix. |
| Windows: SmartScreen warning | Choose More info, Run anyway. |
| MCP: "Port 47321 is already in use" | Another lumetrope-mcp is running. Stop it or set LUMETROPE_MCP_PORT. |
| MCP badge missing | You are on a deployed web copy. Use the desktop app. See MCP. |
| Self-hosted copy loads slowly | Serve .wasm as application/wasm. See web app. |