Was in 3.4.5:
E/cv::error(): OpenCV(3.4.5) Error: Requested object was not found (Layer with requested id=-1 not found) in cv::dnn::experimental_dnn_34_v11::LayerData& cv::dnn::experimental_dnn_34_v11::Net::Impl::getLayerData(int), file /build/3_4_pack-android/opencv/modules/dnn/src/dnn.cpp, line 1271
E/org.opencv.dnn: dnn::forward_14() caught cv::Exception: OpenCV(3.4.5) /build/3_4_pack-android/opencv/modules/dnn/src/dnn.cpp:1271: error: (-204:Requested object was not found) Layer with requested id=-1 not found in function 'cv::dnn::experimental_dnn_34_v11::LayerData& cv::dnn::experimental_dnn_34_v11::Net::Impl::getLayerData(int)'
A/libc: Fatal signal 11 (SIGSEGV), code 1, fault addr 0x10 in tid 29685 (Thread-878)

And in 3.4.9:
E/cv::error(): OpenCV(3.4.9) Error: Requested object was not found (Layer with requested id=-1 not found) in cv::dnn::experimental_dnn_34_v15::LayerData& cv::dnn::experimental_dnn_34_v15::Net::Impl::getLayerData(int), file /build/3_4_pack-android/opencv/modules/dnn/src/dnn.cpp, line 1322
E/org.opencv.dnn: dnn::forward_14() caught cv::Exception: OpenCV(3.4.9) /build/3_4_pack-android/opencv/modules/dnn/src/dnn.cpp:1322: error: (-204:Requested object was not found) Layer with requested id=-1 not found in function 'cv::dnn::experimental_dnn_34_v15::LayerData& cv::dnn::experimental_dnn_34_v15::Net::Impl::getLayerData(int)'
E/AndroidRuntime: FATAL EXCEPTION: Thread-862
    Process: com.example.opencvv3, PID: 28907
    CvException [org.opencv.core.CvException: cv::Exception: OpenCV(3.4.9) /build/3_4_pack-android/opencv/modules/dnn/src/dnn.cpp:1322: error: (-204:Requested object was not found) Layer with requested id=-1 not found in function 'cv::dnn::experimental_dnn_34_v15::LayerData& cv::dnn::experimental_dnn_34_v15::Net::Impl::getLayerData(int)'
    ]
        at org.opencv.dnn.Net.forward_4(Native Method)
        at org.opencv.dnn.Net.forward(Net.java:395)
        at com.example.opencvv3.MainActivity.onCameraFrame(MainActivity.java:136)
        at org.opencv.android.CameraBridgeViewBase.deliverAndDrawFrame(CameraBridgeViewBase.java:392)
        at org.opencv.android.JavaCameraView$CameraWorker.run(JavaCameraView.java:373)
        at java.lang.Thread.run(Thread.java:818)