karatelabs/karate · error · RuntimeException

expected Feature or FeatureCall, got:

Error message

expected Feature or FeatureCall, got: 

What it means

The call step executor expects its evaluated feature argument to be either a Feature object or a FeatureCall; anything else means the argument was not resolvable to a callable feature. The error includes the actual Java class found, making it a type-validation failure for the `call`/`callonce` keyword's argument.

Solutions

1. Ensure the called variable is a feature path string passed through read(): `call read('other.feature')`
2. print the variable to see its actual type before the call
3. If you want call results, use `def res = call ...` and access res.response, do not call the result again
4. Assign the feature explicitly: def f = read('other.feature') then call f

Example fix

// before
* def data = { a: 1 }
* call data
// after
* call read('other.feature')

// karate
* if (!(typeof featureRef == 'string') && !featureRef.read) karate.fail('not a feature ref')

function isFeatureRef(v) { return typeof v === 'string' || (v && typeof v === 'object' && !!v.read); }

When it happens

Trigger: `call <expr>` where expr evaluates to a Map, String, List, or other object that is neither Feature nor FeatureCall — e.g. calling a JSON variable, or a variable set to the result of a previous call (call result object) rather than a feature reference.

Common situations: Mistyping a variable name so `call foo` picks up a data table or response payload instead of the feature; calling the result of another call (`* def r = call x ... * call r`) which is a result wrapper, not a FeatureCall; version migration where call results changed shape.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• call with tag selector requires a feature context
• called feature failed
• same-file tag call requires a feature context
• call expression must resolve to a feature path:
• boot.ext(' '): does not implement io.karatelabs.core.Ext

AI-assisted analysis of karatelabs/karate@a22eb90246 (2026-09-12). Data as JSON: /api/errors/69e70615893940e6. Report an issue: GitHub.

Appendix: source

Thrown at karate-core/src/main/java/io/karatelabs/core/StepExecutor.java:2771

        Feature calledFeature;
        String tagSelector = null;

        if (featureObj instanceof FeatureCall) {
            FeatureCall fc = (FeatureCall) featureObj;
            if (fc.isSameFile()) {
                calledFeature = fr != null ? fr.getFeature() : null;
                if (calledFeature == null) {
                    throw new RuntimeException("same-file tag call requires a feature context");
                }
            } else {
                calledFeature = fc.getFeature();
            }
            tagSelector = fc.getTagSelector();
        } else if (featureObj instanceof Feature) {
            calledFeature = (Feature) featureObj;
        } else {
            throw new RuntimeException("expected Feature or FeatureCall, got: " + featureObj.getClass());
        }

        // Karate-expression eval handles inline JSON with embedded `#(...)`,
        // arrays, variables, and bare JS uniformly.
        Object argObj = argExpr == null ? null : evalKarateExpression(argExpr);

        // Check if it's an array loop call
        if (argObj instanceof List) {
            List<Map<String, Object>> results = callFeatureLoop(calledFeature, (List<?>) argObj, tagSelector, null);
            if (resultVar != null) {
                runtime.setVariable(resultVar, results);
            }
            return;
        }

        // Single call with Map argument
        Map<String, Object> callArg = null;
        if (argObj instanceof Map) {

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