Pdfjs print button does not work with PyQt5

The print task is not enabled in Qt WebEngine so the fault is displayed (I'm still trying to get the data). But in the case of the download button of the PDF it is possible and for this you must use the downloadRequested signal of the QWebEngineProfile:

import os
import sys
from PyQt5 import QtCore, QtWidgets, QtWebEngineWidgets

CURRENT_DIR = os.path.dirname(os.path.realpath(__file__))

PDFJS = QtCore.QUrl.fromLocalFile(
    os.path.join(CURRENT_DIR, "pdfjs/web/viewer.html")
).toString()


class PdfReport(QtWebEngineWidgets.QWebEngineView):
    def __init__(self, parent=None):
        super(PdfReport, self).__init__(parent)
        QtWebEngineWidgets.QWebEngineProfile.defaultProfile().downloadRequested.connect(
            self.on_downloadRequested
        )

    def load_pdf(self, filename):
        url = QtCore.QUrl.fromLocalFile(filename).toString()
        self.load(QtCore.QUrl.fromUserInput("%s?file=%s" % (PDFJS, url)))

    def sizeHint(self):
        return QtCore.QSize(640, 480)

    @QtCore.pyqtSlot(QtWebEngineWidgets.QWebEngineDownloadItem)
    def on_downloadRequested(self, download):
        path, _ = QtWidgets.QFileDialog.getSaveFileName(
            self, "Save File", "sample.pdf", "*.pdf"
        )
        if path:
            download.setPath(path)
            download.accept()


if __name__ == "__main__":

    app = QtWidgets.QApplication(sys.argv)
    w = PdfReport()
    path = os.path.join(CURRENT_DIR, "file0.pdf")
    w.load_pdf(path)
    w.show()
    sys.exit(app.exec_())