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  4. [SOLVED] QSocketNotifier: Can only be used with threads started with QThread
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[SOLVED] QSocketNotifier: Can only be used with threads started with QThread

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  • L Offline
    L Offline
    Leon
    wrote on last edited by
    #1

    My application is coded with qt4
    i added this to the .pro file @QT += widgets@

    to remove the #include errors on qt5.

    Now i have this warning:
    @Starting /home/citybong/Downloads/build-wallch-Desktop-Debug/wallch...
    QSocketNotifier: Can only be used with threads started with QThread
    QSocketNotifier: Can only be used with threads started with QThread@

    which i don't know what it is, what causes it, and how to fix it.

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    • A Offline
      A Offline
      alexandros
      wrote on last edited by
      #2

      I am trying to build a project here which doesn't even use the QSocketNotifier library.

      What?

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      • SGaistS Offline
        SGaistS Offline
        SGaist
        Lifetime Qt Champion
        wrote on last edited by
        #3

        But internally it might be used.

        That question might find better answer on the mailing list (you'll find Qt's developers/maintainers there, this forum is more user oriented)

        Interested in AI ? www.idiap.ch
        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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        • A Offline
          A Offline
          alexandros
          wrote on last edited by
          #4

          If it is internally used (by some other library) and that causes the problem, then I don't have control over it! Why does it complain to me?

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          • JKSHJ Offline
            JKSHJ Offline
            JKSH
            Moderators
            wrote on last edited by
            #5

            [quote author="alexandros" date="1375132190"]If it is internally used (by some other library) and that causes the problem, then I don't have control over it! Why does it complain to me?[/quote]Because it needs you to use your classes differently.

            Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

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            • D Offline
              D Offline
              dbzhang800
              wrote on last edited by
              #6

              Hi, normally, the error will occur when you access a non-thread-safe object which is created in another thread, in other words, wrong usage of QThread will cause this problem.

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              • L Offline
                L Offline
                Leon
                wrote on last edited by
                #7

                Well apparently it had something to do with QFileSystemWatcher
                Fixed ;)

                Z 1 Reply Last reply
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                • L Leon

                  Well apparently it had something to do with QFileSystemWatcher
                  Fixed ;)

                  Z Offline
                  Z Offline
                  Zerhynn
                  wrote on last edited by
                  #8

                  @Leon said in [SOLVED] QSocketNotifier: Can only be used with threads started with QThread:

                  Well apparently it had something to do with QFileSystemWatcher
                  Fixed ;)

                  Leon didn't say what it had to do with the QFileSystemWatcher. For future googlers out there, what worked for me was to make sure the QThread had called its start() function first before utilizing the FileSystemWatcher's signals and slots, i.e. don't do it in the construction.

                  Not sure if that'l work for everyone but it fixed my problem.

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