Using QWebview gives compiling errors, but not because Qt += webkit is missing from the .pro file

Question

I made a project in Qt and added a QWebview to it then I added Qt += webkit to the .pro file. However, upon compiling, I get these to errors:

...ui_mainwindow.h:42: error: undefined reference to `_imp___ZN8QWebViewC1EP7QWidget'
...ui_mainwindow.h:45: error: undefined reference to `_imp___ZN8QWebView6setUrlERK4QUrl'

The errors refer to here (in ui_mainwindow.h):

...
    webView = new QWebView(centralWidget); // <-- First error here
    webView->setObjectName(QStringLiteral("webView"));
    webView->setGeometry(QRect(0, 0, 300, 200));
    webView->setUrl(QUrl(QStringLiteral("about:blank"))); // <-- Second error here
    MainWindow->setCentralWidget(centralWidget);
...

In Program.pro:

QT       += core gui webkit

I think those errors usually occur without Qt += webkit, but in this case that's not what's happening.

Answer 1

...ui_mainwindow.h:42: error: undefined reference to `_imp___ZN8QWebViewC1EP7QWidget'

The linker does not find the the webview widget symbol.

I think those errors usually occur without Qt += webkit, but in this case that's not what's happening.

That is correct, however the QtWebkit module was split into webkit and webkitwidgets in Qt 5 because the widgets were moved usually into their separate module in Qt 5 since the way of building UIs is QtQuick as promoted.

To fix this, you would need to write this in your project file:

QT = webkit webkitwidgets

Note that it is unnecessary to use the core and gui modules explicitly since they are added by default. Also, make sure you have the webkitwidgets module installed, too, otherwise even the above will not be enough.