What else does Qt5Network require when deployed? - qt

I have successfully deployed my Qt application, with all the necessary dll files, and it works fine. However, as soon as I add something which uses Qt5Network, my program crashes with "The application was unable to start correctly (0xc000007b)".
I of course copied the Qt5Network.dll to my deployment dir, and I used a dependency walker, and found out that there was one new dependency compared to what I had before adding the "network" part: libgcc_s_seh-1.dll
I copied that as well, still the same error.
I learned that Qt Network requires OpenSSL, so I found libeay32 and ssleay32, and copied them to my deployment directory as well.
The error is the same. If I remove the requirement for Qt5Network, my program runs fine, and it uses many other modules, like Printsupport, Serialport, etc. without problem.
I tried it on Qt 5.9 and 5.15.

The official Qt binaries (Qt Network in your case) will try to load OpenSLL when first needed, at runtime, not when you first launch your application, see the SSL section here. And I believe that's the reason why dependency walker and windeployt were not able to identify OpenSSL as they can only identify load-time dependendencies.
It seems you were trying to bundle the OpenSSL binaries from an incompatible version. Starting with Qt 5.12.4 the supported OpenSSL version is 1.1.1, see for instance here. If you find the binaries from v1.1.1 and bundle those, your application should work.

Related

Unable to run qt-creator executable outside ide compiled in release mode

After switch to release mode to build a small project I have, when I try run it from inside the qt-creator ide, all goes fine. But when I go to the folder build-<project_name>-Desktop_Qt_5_14_1_MinGW_64_bit- Release and try run the executable generated in this directory, I got this error:
Anyone knows what the problem here? If it was some missing dll, I supose it will specify what dll was missing, right? Or I am mistaken?
update
After run windeployqt, this command found dependencies for my application, create some folders, but now I am getting tis error when try to run it:
update 2
after run the utilitary dependency walker, i got this errors on it:
I am using this build kit to build the project in qt-creator:
Here is all I know about Qt deployment & issues on Windows.
Check whether Release configuration of your project doesn't contain links to any debug versions of libraries.
Build your app in Release mode. Use Rebuild, If in doubt. See compile output window in the IDE, what paths it actually uses.
Use windeployqt tool to automatically copy all the necessary Qt dlls to the executable's folder. Be sure you are using windeployqt.exe from the correct folder. For example, currently I have one version of Qt framework, but two versions of windeployqt: for x86 and x64 compilers. In the case you have more than one version of Qt installed, you may have several versions of the tool.
.
C:\Qt\Qt5.14.1\5.14.1\msvc2017\bin\windeployqt.exe
C:\Qt\Qt5.14.1\5.14.1\msvc2017_64\bin\windeployqt.exe
Copy compiler libraries to the release folder. Make sure that you're copying libraries from the exact compiler you used to build.
Copy all necessary additional 3-rd party dynamic libraries. Make sure it is not debug versions.
If the problem persists, press Ctrl+C when the error message is active. It will copy all the text from the message box. Paste main part of the message to Google.
If the problem persists, open your .exe file in some dll-dependency viewer. Here is how I can see this in Lister. Be note that such a tool will show you not only missing dlls, but also a full path for each dll that your executable actually use. More power tool is Dependency Walker.
Make sure your application doesn't try to write something to a system protected folder, such as c:\Program Files\, without corresponding privileges.
If the problem still persists, simplify your project as much as possible. Run Release for an empty project. Than add modules, functionality and libraries step-by-step.
If everything is okay, test the application on a completely clean virtual machine.
Edit. I google your error text and what I found:
https://stackoverflow.com/a/52127944/
The problem was that windeployqt was unable to locate gcc for some
reason. I added it to my path from cmd with SET
PATH=%PATH%;C:\Qt\Tools\mingw530_32\bin. After I ran windeployqt
again, I did not have to copy libgcc_s_dw2-1.dll and
libwinpthread-1.dll over manually and it used the correct Qt5Core.dll,
since the application is now working fine.

Problems with deploying Qt5 application on windows

So I have Visual Studio 2013 (community edition) with Qt addin installed, Qt5 libraries (32bit), and I'm trying to create an executable that is independent of all development configurations (it may use static or shared libs, I don't really care at this point).
OS: Windows 7, x64.
For doing this I changed the Solution Confguration visual studio option from Debug to Release, and add all the necessary libs in Configuration Properties -> Linker -> Input -> Additional Dependencies. The application now starts only if I run it from visual IDE, If I try to start it from the generated .exe I got The application was unable to start correctly (0xc000007b) error.
I have searched and found that this error code indicates one of the following problems:
32-bit app tries to load a 64-bit DLL (not my case I think, Qt DLLs are 32bit (I have installed using this .exe: qt-opensource-windows-x86-msvc2013-5.5.0.), and I use some other .DLLs which are also 32bit).
There are some missing DLLs. (I did copy all the necessary Qt DLLs in the same folder with the final executable).
For checking what dependencies my app requires, I opened the .exe file with Dependency Walker application, this is what it shows me:
in this list were also Qt5Multimedia.dll and Qt5SerialPort.dll, I get rid of the errors by copying the .DLLs in the same folder with the .exe.
Any ideas how to solve this?
You should never do that operation manually unless the standard procedure completely fails. There is already standard tool for Qt Windows deploymend windeployqt.
It takes care about Qt DLL dependencies, makes a copy of platforms\qwindows.dll and also it makes a copy of libraries that you cannot detect with the Dependency Walker, since image plugins and some other are loaded at runtime.
You do not even need to have your Qt bin folder in your environment PATH. The simplest deployment:
copy built exe binary to a new folder
open cmd console in that folder
call windeployqt using its full path (if it is not in the system PATH) and provide your executable, for example:
c:\Qt\Qt5.5.1-vs2013-x64\5.5\msvc2013_64\bin\windeployqt.exe application.exe
As a result you have in that folder all needed Qt DLLs. Of course you can have also issues with MSVC redistributables, but those should be deployed separately and installed once per system.
The tool windeployqt has various options. It can also take care about deployment of qml related files.
Only some 3rd party libraries should be copied manually if they are used, for example OpenSSL.
Solution:
As I got deeper, I have found this answer, after doing what that answer indicates (I actually copied all the .DLLs located in \Qt5.5.0\5.5\msvc2013\bin to the folder where my .exe is located), the error message changed from The application was unable to start correctly (0xc000007b) to Application failed to start because it could not find or load the QT platform plugin “windows”.
Searching on web for more about this error, I have found from this answer that you also need the platforms folder in the same location with the .exe (which was located in Qt5.5.0\5.5\msvc2013\plugins path). After copying that folder, the application started without any problems!!!
Now I just need to delete all unnecessary .DLLs from my application folder (Dependency Walker does not offer very useful information about this), and all the deployment is done.
I have solved the problem in the same time as describing it, so I guess I will just leave this here, may help others that have the same problem.

Deploying Qt C++ Application from Visual Studio qwindows.dll error

I've been googling for a solution to this issue and although I've found many people sharing my problem none of their solutions work for me.
I wrote a C++ application using Qt framework using Visual Studio 2010. I built and ran the application in "Release" mode from Visual Studio without issue, but when I copy that exe from the Release folder to a new destination (pretend its a new PC) it fails to run providing this error:
---------------------------
TestApplication
---------------------------
This application failed to start because it could not find or load the Qt platform plugin "windows".
Available platform plugins are: windows.
Reinstalling the application may fix this problem.
Within the executable directory I have the following file structure:
./TestApplication.exe
./libGLESv2.dll
./Qt5Core.dll
./Qt5Gui.dll
./QtWidgets.dll
./platforms/qwindows.dll
./qt.conf
All dll files were taken from the 5.0.0 build of Qt in the Qtbase folder where the libraries reside.
The qt.conf file is:
[Paths]
Plugins=.
Without it, the launch error is the same except it says "minimal" and "offscreen" are available platforms as well.
For all other people experiencing this error it seemed to be solved by creating the platforms folder and putting in the qwindows.dll. But doing that myself doesn't change any behavior.
Is there something I've done wrong? Perhaps my method of generating the .exe in the first place is wrong?
If you are using libGLESv2.dll, then you must include libEGL.dll, too.
You can't see that in depends.exe, don't know how the Qt developers managed to hide this.
If your Qt is out of the box, then both Dlls are necessary even if you are not using OpenGL.
Also, if your Qt is out of the box, you need to include also the three ic*.dll, which contain information for Unicode handling.
You can see which DLLs are needed by looking at which ones are invoked when running Debug (F5) in Qt Creator.
=Carl
The release is likely missing a library/plugin or the library is in the wrong directory and or from the wrong directory.
Qt intended answer: Use windeployqt.
Qt comes with platform console applications that will add all dependencies (including ones like qwindows.dll and libEGL.dll) into the folder of your deployed executable. This is the intended way to deploy your application, so you do not miss any libraries (which is the main issue with all of these answers). The application for windows is called windeployqt. There is likely a deployment console app for each OS.

How to make Qt aware of the QMYSQL driver

I'm trying to access a MySql database from a Qt application but I get the following error:
QSqlDatabase: QMYSQL driver not loaded
QSqlDatabase: available drivers: QSQLITE QSQLITE2
I find this very strange cause I have libqsqlmysql.so on my Qt folder. I have even tried to compile the MySql driver as a static plugin and add it to my .pro file as:
QTPLUGIN += qsqlmysql
But this also generates the same runtime error (it must've found the plugin cause there's no error compiling the application)
What am I missing? I would like to avoid having to compile Qt from source cause this will have to work seamlessly on the deploy machines as well.
BTW: Even though I'm developing and testing on Linux I will need to support Windows. Will I experience this same issue on Windows? How can I compile and link the MySql driver in both Linux and Windows?
The solution:
After following #Sergey's recommendations I did an strace of the application redirecting the output to grep so I could search for 'mysql' and for my surprise the application wasn't looking for the plugin at QTDIR/plugins/sqldrivers where I had libqsqlmysql.so, it was looking at QTDIR/lib. After copying the plugin to the lib folder the MySql connection worked.
Try opening the shared library with dlopen() and see if it loads and if not, what dlerror() tells you. I always run into similar problems on Windows. LoadLibrary()/GetLastError() saved me numerous times (last time it was because of a wrong version of some libiconv/libintl DLL). Running ldd on the plugin may also help.
If dlopen() works fine, try to load the plugin with QPluginLoader. If it doesn't load, then check the buildkey of the plugin. I usually do it the dirty way by running strings on the plugin and then looking for strings like "buildkey" or "QT_PLUGIN_VERIFICATION_DATA". Just looking at the build key and around it may give you an idea. For example, you may realize that you have compiled your plugin in the release mode while your application is compiled in the debug mode. In such case the build key won't match and the plugin won't load. Everything in the build key must match your configuration. Note that the version and the build key are checked differently: the build key must match exactly (or match some black magic called QT_BUILD_KEY_COMPAT), but in the version only the major version must match exactly, the minor version must be the version of Qt the plugin was compiled with or later and the patch level is ignored. So if your plugin was compiled with Qt 4.x.y then it will work with Qt versions 4.z.* where z>=x. This actually makes sense.
If the build key looks okay (which is unlikely if you got to this point), you may wish to look at QLibraryPrivate::isPlugin() source code to figure out what's wrong, but that doesn't look like an easy task to me (although running this in a debugger may help).
If QPluginLoader does load the plugin, check if it is in the right directory and has correct permissions. If you still didn't solve the problem by this point, it's time to look at the SQL module source code that actually loads these plugins. But it is extremely unlikely. I ran into this problem many, many times and it was always either the library not loading or the build key not matching.
Another way to go after QPluginLoader loads the plugin successfully is to use strace to figure out whether the program at least tries to open the plugin file. Searching for something like "sqldrivers" or "plugins" in the strace output should also give away the directory where Qt is searching for its plugins and specifically SQL drivers.
Update
Is it possible to compile the driver as a static plugin and don't worry about anything? Let's try:
d:\Qt4\src\plugins\sqldrivers\psql>qmake CONFIG+=static LIBS+=-Ld:/programs/Post
greSQL/lib INCLUDEPATH+=d:/programs/PostgreSQL/include
d:\Qt4\src\plugins\sqldrivers\psql>make
It compiles fine and now I got libqsqlpsql.a (release) and libqsqlpsqld.a (debug) in QTDIR/plugins/sqldrivers (it is the right place on Windows). I am using PostgreSQL driver here, but I don't think it will be any different for MySQL which I just don't have installed. Ok, let's compile some real program with it:
d:\alqualos\pr\archserv>qmake QTPLUGIN+=qsqlpsql PREFIX=d:/alqualos LIBS+=-Ld:/g
nu/lib INCLUDEPATH+=d:/gnu/include LIBS+=-Ld:/programs/PostgreSQL/lib LIBS+=-lpq
Note that I had to manually link to libpq, otherwise the linker would complain about undefined references. The funny thing is, qmake knows that qsqlpsql is located in QTDIR/plugins/sqldrivers and sets compiler and linker options accordingly. So it still needs to be in the right place to work, only you don't have to worry about your users running into the same problem as it is only used during compilation. An alternative would be to just use LIBS+=-Lpath/to/plugin LIBS+=-lqsqlpsql instead of QTPLUGIN+=qsqlpsql, at least the docs say that it should work, but I haven't tested it.
In order for the application to actually use the plugin I had to put the following in my main unit (CPP file):
#include <QtPlugin>
Q_IMPORT_PLUGIN(qsqlpsql)
It works! Also, from what I've been able to figure out from the sources, the build key and the version are checked only when a plugin is dynamically loaded (all the relevant stuff is in the QLibrary's private class, not even QPluginLoader's). So the resulting executable may (or may not, depending on the binary compatibility) work even with different versions and builds of Qt, although using it with older versions may trigger some bugs that were fixed later.
It is also worth noting that the order for loading SQL drivers is this: use the driver statically linked into Qt if available, then look for a driver registered manually with QSqlDatabase::registerSqlDriver(), then look for a driver statically imported into the application (the way described above), and finally try to load a shared plugin. So when you link statically, your users won't be able to use dynamically linked drivers they may already have, but will be able to use drivers linked statically into Qt (like in Ubuntu).
I compiled QT first and then realised that I need mysql as well. So I compiled mysql plugin by
executing following command in QT-DIR\src\plugins\sqldrivers\mysql folder.
Mysql plugin compile command
qmake "INCLUDEPATH+=$$quote(C:\Program Files\MySQL\MySQL Server 5.5\include)" "LIBS+=$$quote(C:\Program Files\MySQL\MySQL Server 5.5\lib\libmysql.lib)" mysql.pro
Plugings are then created in created in folder QT-DIR\plugins\sqldrivers.
However, when I tried to use it in my code. It failed with following error.
Error msg
QSqlDatabase: QMYSQLDriver driver not loaded
Solution
After some googling and checking Path variable I realised that the Mysql server lib
( C:\Program Files\MySQL\MySQL Server 5.5\lib) directory was not in my Path variable. I expect that the dll in this folder are used by the plugin at runtime. After including Mysql server lib in Path variable everything worked smoothly. Hope this information saves some hair on other programmers scalp, as I uprooted quite a few. :D
Last time I looked at this you needed to rebuild Qt from source and include the appropriate MySQL source.
Building Qt from the sources is not hard, it just takes a while. You are likely to have the required tools already.
A possible workaround may be to access the back-end over ODBC instead.
In order for your app to pick up the plugin at runtime, the shared library implementing the MySQL plugin needs to be placed in the correct directory. The best way of determining that directory is to check the output of QCoreApplication::libraryPaths. You can also force specific paths by using a qt.conf file.
Please note that plugins must be placed in subdirectories within the plugin path, and the final part of the path name (i.e., the parent directory of the shared libraries) cannot be changed. SQL drivers need to go in a directory named sqldrivers, i.e. <pluginpath>/sqldrivers. For more details on plugin directories, see How to Create Qt Plugins.
I was experiencing this same issue as well. I've been installing and experimenting with a lot of different Python tools and UIs. I then uninstalled everything python related. I did a fresh install of Python 3.2, PyQT 3.2, and Eric5. No more errors with the QMySQL driver.
well i have had this issue, and after a lot of time, and different tools, i found that QT ( on windows, have not been able to test on Linux.) loads the "QSQLMYSQL.." when requested, but before runtime the lib ("QSQLMYSQL..") file must reside on one of the searched paths (QApp.libraryPaths()) inside a folder called "sqldrivers".. otherwise QT will just ignore the file, even if it is at some other point inside the searched path.
what i did was to monitor the dependency of a sample app, and when i removed the "QSQLMYSQL.." dll from "plugins\sqldrivers\" it failed, but when i maded a folder inside the app folder, called "sqldrivers" and placed the "QSQLMYSQL..." inside there, it loaded.
what i have is mysql 5.5, qt 4.7.4.
hope anyone can use this, and if anyone knows more about it, i would like to know where to find it(http://doc.qt.nokia.com/stable/sql-driver.html, is the closest you can get to the information about the folder structur). :P
This may also happen if your QMYSQL plugin is linked against the "wrong" mysql_client.a or it isn't in the LD_LIBRARY_PATH. I had this problem on OSX because mysql was installed via ports, and I fixed it with:
install_name_tool -change libmysqlclient.18.dylib /usr/local/mysql/lib/libmysqlclient_r.18.dylib libqsqlmysql.dylib

When using py2exe, PyQt application cannot load SQlite database

My PyQt application works fine when running on Linux, when in my Windows build environment, or frozen on the machine where it was build with py2exe. But after moving the frozen executable and its supporting files to another machine it can't load the database driver.
It worked fine when I had Python2.5 and an earlier version of PyQt and py2exe. But after upgrading my toolchain I get these errors:
dbname.open returns false
lastError(dbname) is "Driver not loaded"
I have an sqldrivers folder where I put qsqlite4.dll. This was necessary with the previous build environment, but moving or renaming that DLL doesn't change any behavior. I think that's the DLL that Qt can't find, but I haven't been able to tell Qt where to look.
I am currently running these versions:
python-2.6.3
PyQt-Py2.6-gpl-4.6-1
py2exe-0.6.9.win32-py2.6
Profiling in Dependency Walker gives me this error:
LoadLibraryW("\application\sqldrivers\qsqlite4.dll") returned NULL. Error: This application has failed to start because the application configuration is incorrect. Reinstalling the application may fix this problem (14001).
When I ask Dependency Walker for details about Qsqlite4.dll it says:
Error: The Side-by-Side configuration information for "\application\sqldrivers\QSQLITE4.DLL" contains errors.
That would explain why the DLL won't load, but I'm still unclear how to fix it. Closer inspection shows that error for most of the DLLs I call. Do I need to include a manifest for each Qt DLL I load?
Thanks in advance.
DEAR PEOPLE FROM THE FUTURE: Here's what we've figured out so far ...
The accepted answer doesn't really say what dlls they copied and in what places. I managed to fix it by copying the driver inside the sqldrivers directory relative to where the exe and qt dlls are (I'm using PySide but should work with PyQt4 as well). In setup.py:
setup(
...,
data_files = [('sqldrivers', ('C:\Python27\Lib\site-packages\PySide\plugins\sqldrivers\qsqlite4.dll',))],
...,
)
I solved it!
I had a really clever way to avoid making my users install vcredist--I copied the manifest and the DLLs into two places and all the errors about the MS DLLs went away. That's when I started trying to figure out this SQLite driver error.
I wasn't as smart as I thought. If I install vcredist all the "Driver Not Loaded" and "No SQL drivers found" errors go away. Arg.
Try to re-install SOLite, or verify if you have putted the DLL in the correct place, because i remember that the MySQL DLL have to be in System32 directory to develop something that uses it.
Regards.

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