quarkusio/quarkus · error · RuntimeException

Invalid alpha, number needs to be between 0 and 1. 0 is full

Error message

Invalid alpha, number needs to be between 0 and 1. 0 is fully transparent, 1 is not transparent at all

What it means

The BuildTimeContentProcessor.Color record validates the HSL color components used to generate per-extension Dev UI theme colors. This error is thrown by the Color constructor when alpha is outside 0–1, since alpha is an opacity factor (0 = fully transparent, 1 = fully opaque) — note this is the one component on a 0–1 scale rather than percent.

Source

Thrown at extensions/devui/deployment/src/main/java/io/quarkus/devui/deployment/BuildTimeContentProcessor.java:1347

                throw new RuntimeException(
                        "Invalid hue, number needs to be between 0 and 360. Defines a degree on the color wheel");
            }
            this.hue = hue;

            if (saturation < 0 || saturation > 100) {
                throw new RuntimeException(
                        "Invalid saturation, number needs to be between 0 and 100. 0% is a shade of gray and 100% is the full color (full saturation)");
            }
            this.saturation = saturation;

            if (lightness < 0 || lightness > 100) {
                throw new RuntimeException(
                        "Invalid lightness, number needs to be between 0 and 100. 0% is black, 50% is normal, and 100% is white");
            }
            this.lightness = lightness;

            if (alpha < 0 || alpha > 1) {
                throw new RuntimeException(
                        "Invalid alpha, number needs to be between 0 and 1. 0 is fully transparent, 1 is not transparent at all");
            }
            this.alpha = alpha;
        }

        @Override
        public String toString() {
            return "hsla(" + this.hue + ", " + this.saturation + "%, " + this.lightness + "%, " + this.alpha + ")";
        }

        static Color from(Color color, double alpha) {
            return new Color(color.hue, color.saturation, color.lightness, alpha);
        }

        static Color from(int hue, int saturation, int lightness) {
            return new Color(hue, saturation, lightness, 1);
        }

View on GitHub (pinned to e1c734241f)

Solutions

1. Convert percent alpha to 0–1: alpha = alphaPercent / 100.0
2. Clamp with Math.max(0.0, Math.min(1.0, alpha)) before constructing the Color
3. Fix the hardcoded or computed value to lie within 0–1

Example fix

// before
Color c = new Color(210, 60, 50, 100); // percent, wrong scale
// after
Color c = new Color(210, 60, 50, 100 / 100.0);

double a = alphaPercent / 100.0; // convert percent to 0-1
if (a < 0.0 || a > 1.0) throw new IllegalArgumentException("alpha must be 0-1");

boolean isValidAlpha(double a) { return a >= 0.0 && a <= 1.0; }

try {
    Color c = new Color(hue, sat, light, alpha);
} catch (RuntimeException e) {
    if (e.getMessage().startsWith("Invalid alpha")) {
        c = new Color(hue, sat, light, Math.max(0.0, Math.min(1.0, alpha)));
    } else throw e;
}

When it happens

Trigger: Constructing a Color with a negative alpha or alpha greater than 1 during build-time Dev UI content generation.

Common situations: Passing alpha as a percentage (e.g. 100) when the constructor expects 0–1; using a CSS percent value without dividing by 100; typo in a hardcoded theme value.

Related errors

• Invalid hue, number needs to be between 0 and 360. Defines a
• Invalid saturation, number needs to be between 0 and 100. 0%
• Invalid lightness, number needs to be between 0 and 100. 0%
• An error occurred while processing ${resourceName}
• Failed to read ${extPropsVisitUrl}

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/6fd6cbe85918bf1f. Report an issue: GitHub.