karatelabs/karate · error · DriverException

unknown window operation

Error message

unknown window operation: {operation}

What it means

Driver.window(String) dispatches a named window operation to maximize/minimize/fullscreen/normal. Any other string throws this DriverException listing the unknown operation. The set of operations is intentionally closed so invalid operation names fail loudly rather than silently doing nothing.

Solutions

1. Use one of: 'maximize', 'minimize', 'fullscreen', 'normal' (exact lowercase spelling)
2. For resizing to specific dimensions call driver.setDimensions({ width: ..., height: ... }) instead of window()
3. If the operation name comes from config, validate it against the four allowed values first

Example fix

// before
driver.window("Resize");
// after
driver.setDimensions(Map.of("width", 1024, "height", 768)); // or driver.window("maximize");

java.util.Set<String> ops = java.util.Set.of("maximize","minimize","fullscreen","normal");
if (!ops.contains(operation)) throw new IllegalArgumentException("unknown window op: " + operation);

boolean isWindowOp(String op) { return java.util.Set.of("maximize","minimize","fullscreen","normal").contains(op); }

try { driver.window(op); } catch (DriverException e) { if (e.getMessage().startsWith("unknown window operation")) { /* use setDimensions instead */ } else throw e; }

When it happens

Trigger: Calling driver.window("resize"), driver.window("Maximize") (wrong case), driver.window("fullScreen"), or passing a variable holding an unexpected value.

Common situations: Case-sensitivity mistakes; developers guessing operation names not in the enum-like set; scripts ported from other automation tools with different window API verbs; for arbitrary size changes, window operations are the wrong API (use setDimensions).

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• driver keyword requires a URL argument
• driver URL evaluated to null:
• element not found:
• missing array argument 'patterns':
• missing 'mock' or 'handler' in intercept config

AI-assisted analysis of karatelabs/karate@a22eb90246 (2026-09-12). Data as JSON: /api/errors/8dfd95fffb09aba6. Report an issue: GitHub.

Appendix: source

Thrown at karate-core/src/main/java/io/karatelabs/driver/Driver.java:571

            switchFrame((String) null);
        } else if (target instanceof Number n) {
            switchFrame(n.intValue());
        } else {
            switchFrame(target.toString());
        }
    }

    /**
     * Window management. Dispatches to maximize(), minimize(), fullscreen().
     */
    @Override
    default void window(String operation) {
        switch (operation) {
            case "maximize" -> maximize();
            case "minimize" -> minimize();
            case "fullscreen" -> fullscreen();
            case "normal" -> setDimensions(Map.of("windowState", "normal"));
            default -> throw new DriverException("unknown window operation: " + operation);
        }
    }

    /**
     * Tab switching. Dispatches to {@link #switchPage(int)} or {@link #switchPage(String)}.
     */
    @Override
    default void tab(Object target) {
        if (target instanceof Number n) {
            switchPage(n.intValue());
        } else {
            switchPage(target.toString());
        }
    }

    // ========== Navigation ==========

    /**

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