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Read access violation error

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  • Christian EhrlicherC Online
    Christian EhrlicherC Online
    Christian Ehrlicher
    Lifetime Qt Champion
    wrote on last edited by
    #2

    @ivanicy said in Read access violation error:

    So, my question is if there is a way to see a log of the application to see what is really going wrong?

    As always: use a debugger to see where it exactly crashes.

    Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
    Visit the Qt Academy at https://academy.qt.io/catalog

    ivanicyI 1 Reply Last reply
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    • ivanicyI ivanicy

      Hello!

      I have an application that contains a QGraphicsView. This QGraphicsView loads images and items on it. Suddenly, I don't know if it is when I draw more items or when I load the items, the app crashes with the Read access violation error. This causes qt also crash and shut down. I only can see that there is a problem with QTreeWidget::findItems... but I don't know what is it in my case.

      So, my question is if there is a way to see a log of the application to see what is really going wrong?

      Thank you very much!

      artwawA Offline
      artwawA Offline
      artwaw
      wrote on last edited by
      #3

      @ivanicy Like @Christian-Ehrlicher said. Also, you can use qDebug() to output parameters for findItems, so you can actually see on what parameter it crashed.

      For more information please re-read.

      Kind Regards,
      Artur

      ivanicyI 1 Reply Last reply
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      • Christian EhrlicherC Christian Ehrlicher

        @ivanicy said in Read access violation error:

        So, my question is if there is a way to see a log of the application to see what is really going wrong?

        As always: use a debugger to see where it exactly crashes.

        ivanicyI Offline
        ivanicyI Offline
        ivanicy
        wrote on last edited by
        #4

        @Christian-Ehrlicher I use it, but Qt doesn't show me the line that was wrong. Let me show you an image:

        c2a7da67-844b-4597-bc55-3c6de296d897-image.png

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        • artwawA artwaw

          @ivanicy Like @Christian-Ehrlicher said. Also, you can use qDebug() to output parameters for findItems, so you can actually see on what parameter it crashed.

          ivanicyI Offline
          ivanicyI Offline
          ivanicy
          wrote on last edited by
          #5

          @artwaw The problem is that I am not using this function. I think that Qt use it in background when I load the items

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          • Christian EhrlicherC Online
            Christian EhrlicherC Online
            Christian Ehrlicher
            Lifetime Qt Champion
            wrote on last edited by
            #6

            Go up the stack until you see from where findItems() is called. Looks like an infinite loop.

            Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
            Visit the Qt Academy at https://academy.qt.io/catalog

            ivanicyI 1 Reply Last reply
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            • Christian EhrlicherC Christian Ehrlicher

              Go up the stack until you see from where findItems() is called. Looks like an infinite loop.

              ivanicyI Offline
              ivanicyI Offline
              ivanicy
              wrote on last edited by
              #7

              @Christian-Ehrlicher I can't do that because Qt crashes and close.

              Christian EhrlicherC 1 Reply Last reply
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              • ivanicyI ivanicy

                @Christian-Ehrlicher I can't do that because Qt crashes and close.

                Christian EhrlicherC Online
                Christian EhrlicherC Online
                Christian Ehrlicher
                Lifetime Qt Champion
                wrote on last edited by
                #8

                @ivanicy I don't understand. Why can't you go up in the stack trace to see where it crashes? Does the debugger crash?

                Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
                Visit the Qt Academy at https://academy.qt.io/catalog

                ivanicyI 1 Reply Last reply
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                • Christian EhrlicherC Christian Ehrlicher

                  @ivanicy I don't understand. Why can't you go up in the stack trace to see where it crashes? Does the debugger crash?

                  ivanicyI Offline
                  ivanicyI Offline
                  ivanicy
                  wrote on last edited by
                  #9

                  @Christian-Ehrlicher When I try to scroll for the entries Qt doesn't respond and then close itself

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                  • Christian EhrlicherC Online
                    Christian EhrlicherC Online
                    Christian Ehrlicher
                    Lifetime Qt Champion
                    wrote on last edited by
                    #10

                    @ivanicy said in Read access violation error:

                    Qt doesn't respond

                    What do you mean with 'Qt' here? QtCreator? this is not Qt but an IDE...
                    I'm pretty sure you call findItems() somewhere in your code.

                    Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
                    Visit the Qt Academy at https://academy.qt.io/catalog

                    ivanicyI 1 Reply Last reply
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                    • Christian EhrlicherC Christian Ehrlicher

                      @ivanicy said in Read access violation error:

                      Qt doesn't respond

                      What do you mean with 'Qt' here? QtCreator? this is not Qt but an IDE...
                      I'm pretty sure you call findItems() somewhere in your code.

                      ivanicyI Offline
                      ivanicyI Offline
                      ivanicy
                      wrote on last edited by
                      #11

                      @Christian-Ehrlicher Yes, I mean Qt Creator and no, I don't call findItems anywhere. I don't know if QGraphicsScene use it when I call to the addItem function or something like that but I don't call it explicitly.

                      jsulmJ 1 Reply Last reply
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                      • Christian EhrlicherC Online
                        Christian EhrlicherC Online
                        Christian Ehrlicher
                        Lifetime Qt Champion
                        wrote on last edited by
                        #12

                        You have no other chance to either reduce you code until it no longer crashes or write a minimal example to reproduce the problem. Also check if the stuff you pass to addItem() are valid.

                        Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
                        Visit the Qt Academy at https://academy.qt.io/catalog

                        1 Reply Last reply
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                        • ivanicyI ivanicy

                          @Christian-Ehrlicher Yes, I mean Qt Creator and no, I don't call findItems anywhere. I don't know if QGraphicsScene use it when I call to the addItem function or something like that but I don't call it explicitly.

                          jsulmJ Offline
                          jsulmJ Offline
                          jsulm
                          Lifetime Qt Champion
                          wrote on last edited by
                          #13

                          @ivanicy You can also try to disable parts of your code until it stops crashing then you know roughly where it is. And if you use CVS like Git you can check the changes since last stable version.

                          https://forum.qt.io/topic/113070/qt-code-of-conduct

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