fyne-io/fyne · critical

XCreateColormap failed\n

Error message

XCreateColormap failed\n

What it means

After resolving the visual, x11.c creates a colormap for it before creating the window. XCreateColormap returning NULL means the X server refused the allocation: usually resource limits on the server or an exotic visual (DirectColor, unusual depth) rather than TrueColor, for which colormaps are essentially free. The process prints 'XCreateColormap failed' and exits(1).

Solutions

1. Run the X server at 24-bit TrueColor depth where colormap allocation cannot fail: xvfb-run -a -s '-screen 0 1024x768x24' ./yourapp
2. Close leaking X clients or restart the X server / Xvfb instance
3. Check server limits with xdpyinfo | grep -i 'number of' before launching
4. Update the graphics stack if the failure persists on a normal desktop server

Example fix

# before: Xvfb at 8-bit depth, colormap allocation fails
Xvfb :99 -screen 0 1024x768x8 & DISPLAY=:99 ./yourapp

# after: TrueColor 24-bit server, colormap allocation succeeds
Xvfb :99 -screen 0 1024x768x24 & DISPLAY=:99 ./yourapp

func xResourcePreflight() error {
	out, err := exec.Command("sh", "-c", "xdpyinfo | grep -i 'number of clients'").CombinedOutput()
	if err != nil {
		return fmt.Errorf("cannot query X server: %w", err)
	}
	_ = out // server reachable; restart it if colormap resources are exhausted
	return nil
}

When it happens

Trigger: Creating a colormap for visInfo->visual fails on a server at its resource limit, or for a visual class that requires real colormap cells on an 8-bit/pseudocolor or otherwise non-TrueColor server.

Common situations: Long-running or leaky X servers (many clients allocated colormaps/cells); Xvfb started at low depth (8/16-bit); embedded or minimal X servers with tight resource pools.

Related errors

• XGetVisualInfo failed\n
• eglChooseConfig failed\n
• eglCreateWindowSurface failed\n
• eglGetConfigAttrib failed\n
• eglGetDisplay failed\n

AI-assisted analysis of fyne-io/fyne@8860ee95c3 (2026-08-15). Data as JSON: /api/errors/03aa90d9649d3f42. Report an issue: GitHub.

Appendix: source

Thrown at internal/driver/mobile/app/x11.c:56

		fprintf(stderr, "eglGetConfigAttrib failed\n");
		exit(1);
	}

	XVisualInfo visTemplate;
	visTemplate.visualid = vid;
	int num_visuals;
	XVisualInfo *visInfo = XGetVisualInfo(x_dpy, VisualIDMask, &visTemplate, &num_visuals);
	if (!visInfo) {
		fprintf(stderr, "XGetVisualInfo failed\n");
		exit(1);
	}

	Window root = RootWindow(x_dpy, DefaultScreen(x_dpy));
	XSetWindowAttributes attr;

	attr.colormap = XCreateColormap(x_dpy, root, visInfo->visual, AllocNone);
	if (!attr.colormap) {
		fprintf(stderr, "XCreateColormap failed\n");
		exit(1);
	}

	attr.event_mask = StructureNotifyMask | ExposureMask |
		ButtonPressMask | ButtonReleaseMask | ButtonMotionMask;
	Window win = XCreateWindow(
		x_dpy, root, 0, 0, w, h, 0, visInfo->depth, InputOutput,
		visInfo->visual, CWColormap | CWEventMask, &attr);
	XFree(visInfo);

	XSizeHints sizehints;
	sizehints.width  = w;
	sizehints.height = h;
	sizehints.flags = USSize;
	XSetNormalHints(x_dpy, win, &sizehints);
	XSetStandardProperties(x_dpy, win, "App", "App", None, (char **)NULL, 0, &sizehints);

	static const EGLint ctx_attribs[] = {

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