How to solve this OpenCV.dnn Net.forward() access violation exception?


I am experiencing an access violation exception when using OpenCv::dnn::Net forward function.

std::string m_pathCaffeModel;
std::string m_pathConfig;
m_pathCaffeModel = "model.caffemodel";
m_pathConfig = "model.prototxt";
cv::dnn::Net m_net;
m_net = cv::dnn::readNetFromCaffe(m_pathConfig, m_pathCaffeModel);
cv::Mat blob; 
cv::dnn::blobFromImage(resized, blob, 1.0, cv::Size(), cv::Scalar(), false, false, CV_32F);

When I call net.forward() I get the following error:

Exception thrown at 0x00007FFD2C1B12DE (vcruntime140.dll) in my_exe.exe: 0xC0000005: Access violation reading location 0x000001C521201000

I checked the input image (called "resized" in the code) printing and that looks good. Its dimensions and data also look correct.

input image data (called resized)

To me the blob looks suspicious, because it has -1 rows and -1 columns. I don't know if this is a problem. blob

The model accepts 40x40 3-channels images.

Does anyone have a suggestion about what is the cause of the problem and how to fix it?

asked on Stack Overflow Dec 2, 2020 by hammockman • edited Dec 3, 2020 by hammockman

1 Answer


Using C++ and OpenCV::dnn::Net, it is necessary to define some further settings:


(the above for CPU inference)

with these two lines before net.forward() the error disappears and it works.

answered on Stack Overflow Dec 7, 2020 by hammockman

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