m1k1o/neko · error

unsupported screen rate %d

Error message

unsupported screen rate %d

What it means

ChangeScreenSize detects C.BadValue from the X server, which XRandR returns when the requested refresh rate is not supported for the selected mode, and reports 'unsupported screen rate %d'. The configuration call failed specifically because of the Rate field. Note the code also assigns the generic 'unknown screen configuration' error first, so the BadValue branch overwrites it when it applies.

Source

Thrown at server/pkg/xorg/xorg.go:234

	status := C.XSetScreenConfiguration(c_width, c_height, c_rate)
	if status != C.RRSetConfigSuccess {
		// create new screen configuration
		C.XCreateScreenMode(c_width, c_height, c_rate)

		// screen configuration should exist now, set it
		status = C.XSetScreenConfiguration(c_width, c_height, c_rate)
	}

	var err error

	// if screen configuration was not set successfully, return error
	if status != C.RRSetConfigSuccess {
		err = fmt.Errorf("unknown screen configuration %s", s.String())
	}

	// if specified rate is not supported a BadValue error is returned
	if status == C.BadValue {
		err = fmt.Errorf("unsupported screen rate %d", s.Rate)
	}

	return s, err
}

func GetScreenSize() types.ScreenSize {
	mu.Lock()
	defer mu.Unlock()

	c_width, c_height, c_rate := C.int(0), C.int(0), C.short(0)
	C.XGetScreenConfiguration(&c_width, &c_height, &c_rate)

	return types.ScreenSize{
		Width:  int(c_width),
		Height: int(c_height),
		Rate:   int16(c_rate),
	}
}

View on GitHub (pinned to b0f01cedea)

Solutions

1. Request a refresh rate listed in the XRandR mode list for the chosen resolution (xrandr -q)
2. Omit/normalize the rate: pick the mode's default rate instead of a hardcoded value
3. Cache and refresh supported rates via GetScreenSize/RRGetScreenInfo before applying
4. Add a cvt/xrandr modeline for exotic rates if the hardware truly supports them

Example fix

// before
xorg.SetScreenSize(types.ScreenSize{Width: 1920, Height: 1080, Rate: 144})
// after
mode := pickMode(supportedModes, 1920, 1080) // rate from xrandr query
xorg.SetScreenSize(types.ScreenSize{Width: 1920, Height: 1080, Rate: mode.Rate})

// validate the rate against modes reported by the X server
modes := queryXRandRModes(width, height)
func rateSupported(rate uint32, modes []Mode) bool {
    for _, m := range modes {
        if m.Rate == rate { return true }
    }
    return false
}

func isUnsupportedRate(err error) bool {
    return err != nil && strings.Contains(err.Error(), "unsupported screen rate")
}

s, err := xorg.SetScreenSize(want)
if isUnsupportedRate(err) {
    // retry with the mode's default rate
    want.Rate = defaultRateFor(want.Width, want.Height)
    s, err = xorg.SetScreenSize(want)
}

When it happens

Trigger: Calling ChangeScreenSize/SetScreenSize with a ScreenSize whose Rate is not offered by the X server for the given resolution (e.g. Rate 144 on a 60 Hz panel).

Common situations: Clients letting users pick arbitrary refresh rates; presets copied from another machine; HiDPI/TV modes supporting only 24/30/60 Hz; fractional rates (59.94) requested as integers.

Related errors

• unknown screen configuration %s
• unknown touch id %v
• debounced button %v
• debounced key %v

AI-assisted analysis of m1k1o/neko@b0f01cedea (2026-09-01). Data as JSON: /api/errors/33f5a67309bc1321. Report an issue: GitHub.