karatelabs/karate · error · RuntimeException

Failed to evaluate

Error message

Failed to evaluate {}: {}

What it means

Evaluating the karate config JavaScript (karate-config.js or a named variant) threw an exception. Karate logs the message and then rethrows a RuntimeException "Config evaluation failed: <displayName> - <reason>", aborting scenario startup. This is a hard failure, unlike the non-object return case.

Solutions

1. Read the '{}' detail in the log/exception — the underlying JS error — and fix that line in the config script.
2. Run the config body in a plain JS engine or node to reproduce and debug the error.
3. Guard environment-dependent code: `var env = karate.env || 'dev';` and null-check system properties.
4. Keep a minimal known-good karate-config.js and bisect additions until the failure disappears.

Example fix

// before
var key = java.lang.System.getProperty('secret.key').trim();
// after
var key = java.lang.System.getProperty('secret.key');
if (!key) key = 'default';

// smoke-test the config before running suites
karate.env = karate.env || 'dev';
if (!karate.env) throw new Error('karate.env missing');

try { vars = evalConfigJs(...); } catch (e) { throw new RuntimeException("Config evaluation failed: " + displayName + " - " + e.getMessage(), e); }

When it happens

Trigger: JS syntax error or runtime exception (undefined variable, calling missing function, etc.) inside karate-config.js / evalConfigJs while evalConfig initializes the scenario context.

Common situations: karate.env not handled (switch on undefined); typo in karate.* API usage; reading a system property that is null and calling methods on it; broken config after refactor or merge conflict.

Related errors

• a class declaration may not be the body of
• a function declaration may not be the body of
• a lexical declaration may not be the body of
• 'await' is a reserved word in a class static initialization…
• 'break' may not cross a class static initialization block

AI-assisted analysis of karatelabs/karate@a22eb90246 (2026-09-12). Data as JSON: /api/errors/5c6c6e82e121573b. Report an issue: GitHub.

Appendix: source

Thrown at karate-core/src/main/java/io/karatelabs/core/ScenarioRuntime.java:503

            } else {
                // Already evaluated to a value (e.g., object literal)
                result = fn;
            }

            // Apply config variables to engine
            if (result instanceof Map) {
                Map<String, Object> vars = (Map<String, Object>) result;
                for (var entry : vars.entrySet()) {
                    karate.engine.put(entry.getKey(), entry.getValue());
                }
                logger.debug("Evaluated {}: {} variables", displayName, vars.size());
                return vars;
            } else if (result != null) {
                logger.warn("{} did not return an object, got: {}", displayName, result.getClass().getSimpleName());
            }
            return null;
        } catch (Exception e) {
            logger.warn("Failed to evaluate {}: {}", displayName, e.getMessage());
            throw new RuntimeException("Config evaluation failed: " + displayName + " - " + e.getMessage(), e);
        }
    }

    /**
     * Execute the @setup scenario and return all its variables.
     */
    public Map<String, Object> executeSetup(String name) {
        if (featureRuntime == null) {
            throw new RuntimeException("karate.setup() requires a feature context");
        }
        Scenario setupScenario = scenario.getFeature().getSetup(name);
        if (setupScenario == null) {
            String message = "no scenario found with @setup tag";
            if (name != null) {
                message = message + " and name '" + name + "'";
            }
            throw new RuntimeException(message);

View on GitHub (pinned to a22eb90246)