QtWebEngineCore.dll SOMETIMES not found

[Volker75]

Hallo,

I wrote an Qt 6 (Currently Qt 6.7.2) application, that #include <QWebEngineView>
I can compile it and run the application.
So far everything is working fine.
I can also compile with Windows, Linux and MacOS. All is running fine.
I always use the deploy tools, so it copy the needed dll and so files automatically into to correct folders.
I can copy the Windows, Linux and MacOS versions on other computers and they always run fine.
I tested that at least on 10 different Windows computers.

But now a user reports that he get an error message "QtWebEngineCore.dll not found". But the file is in the correct directory. I visited that user and check that the dll is at the correct place. We even deleted the whole folder and unzip the software once again (the software that is running fine on 10 other Windows computers). I saw again the dll at the correct place, but he still get the warning about the missing dll file.

Then I right clicked on the QtWebEngineCore.dll to view the properties and I noticed that his computer needs over 5 seconds to open the "right click contents menu"! But the error is always reported immediately if i try to run the application. So I guess that something (maybe a Virus scanner) tries to check the dll file before opening it and that took too much time (since the dll file is ~140MB large). Sadly I can't see everything on that PC and also not the other user, since it is a remote Windows Server used with Citrix.

Is there a way to increase the number of read accesses if opening a dll file fails? Or is it possible to increasing the time limit before a bug is reported?

I guess static compiling might solve it, but i never done that so far and, if I understood correct, there might be a legal problem with my software if i compile static. Of course we might try to fix that problem on the server, but the problem with that fix will be, that it helps only that single user. A fix should help all users, so I prefer a fix by Qt or my source. Any other ideas how to fix that?

Thank you for your help

[JonB]

@Volker75
Start by switching off virus scanning if you really think that is an issue.

I believe Windows reports "DLL not found" for a "top-level" DLL when, although it can find it, it has further dependent DLLs and it cannot find one of those. Check QtWebEngineCore.dll's dependencies on the bad system. Check none of them are on a remote/network/slow drive. Check the user's PATH does not have such a drive on it.

[Volker75]

Thank you for answer. I will try. It will take some time, since the other user is not the admin and the admin is located at an other location. I will visit the user in 2 days again.
I can't say where the drives are, if they are local or over network. I guess network, since it is a very large institution (a server that cares about several thousand users). So i fear the admin will not disable virus checking, since it is a system in use. The admin is for sure not allowed to disable security systems. Maybe he has got a test platform. I will ask him.

[SGaist]

Hi,

One other thing to check is whether there is another version of Qt deployed somewhere in a folder that is in the PATH environnement variable. This one might be loaded first and thus break things on your side.
This could be easier to debug, start a terminal, make PATH to its minimal version and try to start your application.

[Volker75]

Good idea. I will try it.