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().

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;

View on GitHub (pinned to 157c9d86ac)

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.
• null camera target
• Could not find requested camera.
• Could not find suitable preview frames per second range.
• Cannot advance the iterator beyond

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