Hey, my client application needs to send files of ~1-100MB to my rest api which expects a FormFile . I have looked around for a bit and found QHttpMultiPart , which seemed to be a reasonable solution to my problem. I have tried a small example to see if it is working correctly. It seems to work just fine for small files (.txt files with some words of content), but if the file is getting a bit bigger (100KB pdf file) my Qt application just freezes. This is the code that I have been using: // Open file QFile* file = new QFile("/home/creapermann/Downloads/api-design.pdf"); if(!file->open(QIODevice::ReadOnly | QIODevice::Text)) { qDebug() << "Could not open test file!"; return; } QHttpMultiPart* multiPart = new QHttpMultiPart(QHttpMultiPart::FormDataType); QHttpPart filePart; filePart.setHeader(QNetworkRequest::ContentTypeHeader, QVariant("multipart/form-data")); filePart.setHeader(QNetworkRequest::ContentDispositionHeader, QVariant("form-data; name=\"file\"; filename=\"" + file->fileName() + "\"")); filePart.setBodyDevice(file); file->setParent(multiPart); multiPart->append(filePart); QUrl url(serverDomain); QNetworkRequest testRequest { url }; // -- Some Server Specific Headers -- // -- Some SSL configuration code -- auto reply = m_networkAccessManager.post(testRequest, multiPart); m_testReply.reset(reply); linkRequestToErrorHandling(m_testReply.get(), 201); Does anyone have an idea why it might not work correctly? Thanks in advance

I have found the problem... I have called: file->open(QIODevice::ReadOnly | QIODevice::Text) while the file I am reading is not Text , opening the file simply via: file->open(QIODevice::ReadOnly) fixed it.

@ Creaperdown Certainly there is nothing "magical" in Qt to do it. Not my area, but I would start by Googling for, say, can you send big files via http . You state you have a REST API, one hit is https://stackoverflow.com/questions/33889410/proper-way-to-implement-restful-large-file-upload , does this give useful suggestions?

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Using QHttpMultiPart to send big files via HTTP freezes my application

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I have found the problem...

I have called: file->open(QIODevice::ReadOnly | QIODevice::Text) while the file I am reading is not Text, opening the file simply via: file->open(QIODevice::ReadOnly) fixed it.
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