microg/GmsCore · error · IllegalArgumentException

No context supplied.

Error message

No context supplied.

What it means

CameraSource.Builder's constructor throws IllegalArgumentException when the supplied Context is null. A Context is mandatory for the camera source to access camera hardware and application resources, so the library fails fast at build time rather than later at start().

Solutions

1. Pass a valid non-null Context, e.g. activity.getApplicationContext()
2. In a Fragment, obtain the context after onAttach/onCreateView rather than in field initializers
3. Guard the builder call with a null check and fail early with your own message
4. In tests, use an InstrumentationRegistry or Robolectric context instead of null

Example fix

// before
CameraSource.Builder builder = new CameraSource.Builder(context, detector); // context may be null
// after
Context appContext = (context != null) ? context.getApplicationContext() : getApplicationContext();
if (appContext == null) throw new IllegalStateException("Context not ready");
CameraSource.Builder builder = new CameraSource.Builder(appContext, detector);

if (context == null) throw new IllegalStateException("CameraSource needs a non-null Context");

boolean canBuildCameraSource(Context ctx, Detector<?> d) { return ctx != null && d != null; }

try {
    CameraSource.Builder b = new CameraSource.Builder(context, detector);
} catch (IllegalArgumentException e) {
    // context or detector was null; fix initialization
}

When it happens

Trigger: Calling new CameraSource.Builder(null, detector) — typically because an Activity/Context field was not yet initialized, was captured before onCreate, or a mocked/null context was injected in a test.

Common situations: Using getContext() in a Fragment before onAttach; holding a stale activity reference cleared by a configuration change; unit tests passing null context.

Related errors

• No detector supplied.
• Could not find requested camera.
• Could not find suitable preview frames per second range.
• null camera target
• Callable must not be null

AI-assisted analysis of microg/GmsCore@157c9d86ac (2026-09-06). Data as JSON: /api/errors/b83778b2c1ad06e3. Report an issue: GitHub.

Appendix: source

Thrown at play-services-vision-common/src/main/java/com/google/android/gms/vision/CameraSource.java:191

        synchronized (this.cameraLock) {
            if (camera != null) {
                camera.takePicture(shutter::onShutter, null, null, (data, camera) -> jpeg.onPictureTaken(data));
            }
        }
    }

    /**
     * Builder for configuring and creating an associated camera source.
     */
    public static class Builder {
        private CameraSource cameraSource = new CameraSource();

        /**
         * Creates a camera source builder with the supplied context and detector.
         * Camera preview images will be streamed to the associated detector upon starting the camera source.
         */
        public Builder(Context context, Detector<?> detector) {
            if (context == null) throw new IllegalArgumentException("No context supplied.");
            if (detector == null) throw new IllegalArgumentException("No detector supplied.");
            this.cameraSource.context = context;
            this.cameraSource.detector = detector;
        }

        /**
         * Creates an instance of the camera source.
         */
        public CameraSource build() {
            return cameraSource;
        }

        /**
         * Sets whether to enable camera auto focus. If set to false (default), the camera's default focus setting is used. If set to true, a continuous video focus setting is used (if supported by the camera hardware).
         * Default: false.
         */
        public Builder setAutoFocusEnabled(boolean autoFocusEnabled) {
            this.cameraSource.autoFocusEnabled = autoFocusEnabled;

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