导致错误的原因＆＃34; setNativeLocks失败：资源暂时不可用＆＃34;？

Question

我在PyQt中编写此代码，但是当我尝试打开文件时，我收到此错误：

  

setNativeLocks失败：资源暂时不可用

为什么我无法打开并保存文件？

# class Main
class MainWindow(QMainWindow):
    def __init__(self):
        QMainWindow.__init__(self)
        self.setMinimumSize(QSize(300, 300))    
        self.setWindowTitle("TP1") 
        # Create new action
        openAction = QAction(QIcon('open.png'), '&Open', self)        
        openAction.setShortcut('Ctrl+O')
        openAction.setStatusTip('Open document')
        openAction.triggered.connect(self.openCall)
        # Save new action
        saveAction = QAction(QIcon('save.png'), '&Save', self)        
        saveAction.setShortcut('Ctrl+S')
        saveAction.setStatusTip('Save document')
        saveAction.triggered.connect(self.newSave)
        # Copy new action
        copyAction = QAction(QIcon('copy.png'), '&Copy', self)        
        copyAction.setShortcut('Ctrl+C')
        copyAction.setStatusTip('Copy document')
        copyAction.triggered.connect(self.CopyCall)
        # Create exit action
        exitAction = QAction(QIcon('quit.png'), '&Exit', self)        
        exitAction.setShortcut('Ctrl+Q')
        exitAction.setStatusTip('Exit application')
        exitAction.triggered.connect(self.exitCall)
        # Create menu bar and add action
        menuBar = self.menuBar()
        fileMenu = menuBar.addMenu('&File')
        fileMenu.addAction(openAction)
        fileMenu.addAction(saveAction)
        fileMenu.addAction(copyAction)
        fileMenu.addAction(exitAction)

    def openCall(self):
        fileName = QFileDialog.getOpenFileName(self,"Open Image","/home/m1/icheva/a","*.txt")
        print('Open')

    def newSave(self):
        fileName1 = QFileDialog.getSaveFileName(self,"Save File","/home/m1/icheva/a/savefile.txt","*.txt")
        print('Save ')

    def CopyCall(self):
        print('Copy app')

    def exitCall(self):
        print('Exit app')

#main    
if __name__ == "__main__":

    app = QtWidgets.QApplication(sys.argv)
    mainWin = MainWindow()
    mainWin.show()
    sys.exit( app.exec_() )