Cannot mix incompatible Qt library

Tamfub

@Christian-Ehrlicher said in Cannot mix incompatible Qt library:

win32:CONFIG(release, debug|release): LIBS += -L$$PWD/../../../../../5.15.1/mingw81_64/plugins/sqldrivers/mysql-connector-c-6.1.11-winx64/lib/ -llibmysql
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/../../../../../5.15.1/mingw81_64/plugins/sqldrivers/mysql-connector-c-6.1.11-winx64/lib/ -llibmysqld

INCLUDEPATH += $$PWD/../../../../../5.15.1/mingw81_64/plugins/sqldrivers/mysql-connector-c-6.1.11-winx64/include
DEPENDPATH += $$PWD/../../../../../5.15.1/mingw81_64/plugins/sqldrivers/mysql-connector-c-6.1.11-winx64/include
What do you think do gain with this? It's not needed at all.

If I don't include this, I get this while running my program in Qt:

QFactoryLoader::QFactoryLoader() checking directory path "C:/Qt/5.15.1/mingw81_64/plugins/sqldrivers" ...
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/5.15.1/mingw81_64/plugins/sqldrivers/qsqlite.dll"
Found metadata in lib C:/Qt/5.15.1/mingw81_64/plugins/sqldrivers/qsqlite.dll, metadata=
{
    "IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
    "MetaData": {
        "Keys": [
            "QSQLITE"
        ]
    },
    "archreq": 0,
    "className": "QSQLiteDriverPlugin",
    "debug": false,
    "version": 331520
}


Got keys from plugin meta data ("QSQLITE")
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/5.15.1/mingw81_64/plugins/sqldrivers/qsqlmysql.dll"
Found metadata in lib C:/Qt/5.15.1/mingw81_64/plugins/sqldrivers/qsqlmysql.dll, metadata=
{
    "IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
    "MetaData": {
        "Keys": [
            "QMYSQL3",
            "QMYSQL",
            "QMARIADB"
        ]
    },
    "archreq": 0,
    "className": "QMYSQLDriverPlugin",
    "debug": false,
    "version": 331520
}


Got keys from plugin meta data ("QMYSQL3", "QMYSQL", "QMARIADB")
QFactoryLoader::QFactoryLoader() looking at "C:/Qt/5.15.1/mingw81_64/plugins/sqldrivers/qsqlodbc.dll"
Found metadata in lib C:/Qt/5.15.1/mingw81_64/plugins/sqldrivers/qsqlodbc.dll, metadata=
{
    "IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
    "MetaData": {
        "Keys": [
            "QODBC3",
            "QODBC"
        ]
    },
    "archreq": 0,
    "className": "QODBCDriverPlugin",
    "debug": false,
    "version": 331520
}


Got keys from plugin meta data ("QODBC3", "QODBC")
QFactoryLoader::QFactoryLoader() checking directory path "C:/Qt/Projects/tutorial/progettoMalnati/sharedtexteditor/build-progettoMalnati_srv_2-Desktop_Qt_5_15_1_MinGW_64_bit-Release/release/sqldrivers" ...
Cannot load library C:\Qt\5.15.1\mingw81_64\plugins\sqldrivers\qsqlmysql.dll: Impossibile trovare il modulo specificato.
QLibraryPrivate::loadPlugin failed on "C:/Qt/5.15.1/mingw81_64/plugins/sqldrivers/qsqlmysql.dll" : "Cannot load library C:\\Qt\\5.15.1\\mingw81_64\\plugins\\sqldrivers\\qsqlmysql.dll: Impossibile trovare il modulo specificato."
QSqlDatabase: QMYSQL driver not loaded
QSqlDatabase: available drivers: QSQLITE QMARIADB QMYSQL QMYSQL3 QODBC QODBC3
Errore nel collegamento al DB
"Driver not loaded Driver not loaded"

i.e. it cannot load the MYSQL driver. Also, Dependency Walker is taking ages to analyze my .exe. They say it is a normal behaviour, but 5 minutes is too much I guess.

Christian Ehrlicher

@Tamfub said in Cannot mix incompatible Qt library:

If I don't include this, I get this while running my program in Qt:

You're aware that some compiler options and loading a plugin has nothing to do with each other? It's not needed. The only thing you need is (as I already told you) that the program finds the dependencies for your plugin, for instance the mysql dll (search the forum)

Tamfub

@Christian-Ehrlicher
After a long time I managed to analyze the .exe on Dependency Walker, and I got this in the log window:

LoadLibraryW("C:\qt\projects\tutorial\progettomalnati\sharedtexteditor\build-progettomalnati_srv_2-desktop_qt_5_15_1_mingw_64_bit-release\release\sqldrivers\qsqlmysql.dll") called from "QT5CORE.DLL" at address 0x0000000068A61823.
Loaded "QSQLMYSQL.DLL" at address 0x000000006C5C0000.  Successfully hooked module.
Unloaded "QSQLMYSQL.DLL" at address 0x000000006C5C0000.
LoadLibraryW("C:\qt\projects\tutorial\progettomalnati\sharedtexteditor\build-progettomalnati_srv_2-desktop_qt_5_15_1_mingw_64_bit-release\release\sqldrivers\qsqlmysql.dll") returned NULL. Error: Impossibile trovare il modulo specificato (126).
QSqlDatabase: QMYSQL driver not loaded
QSqlDatabase: available drivers: QSQLITE QMARIADB QMYSQL QMYSQL3 QODBC QODBC3
Errore nel collegamento al DB
"Driver not loaded Driver not loaded"

But this file is in the folder!

Christian Ehrlicher

@Tamfub said in Cannot mix incompatible Qt library:

But this file is in the folder!

I know, but you don't read what I tell you (already two times) - the plugins has some dependencies to other libraries which must be available... !

Tamfub

@Christian-Ehrlicher I actually read what you wrote. But I don't get which libraries must be available, then. Maybe I'm missing a LIBS directive in the .pro file?

Christian Ehrlicher

@Christian-Ehrlicher said in Cannot mix incompatible Qt library:

. The only thing you need is (as I already told you) that the program finds the dependencies for your plugin, for instance the mysql dll (search the forum)

...

Tamfub

Hi.

@JKSH said in Cannot mix incompatible Qt library:

I just noticed something else: It looks like you are using 64-bit Qt and 64-bit MinGW. Therefore, you must also use the 64-bit MySQL C connector. (Your screenshots show that you've installed 32-bit MySQL)

I missed this passage. At the moment, I have two choices:

Install 32-bit MySQL - I visited this page but there's no 64-bit version.

Use 32-bit Qt and 32-bit MinGW (both are already installed on my PC) - Qt version can be changed from the "Manage kits" tool, but how do I change the qmake version?

JKSH

@Tamfub said in Cannot mix incompatible Qt library:

@JKSH said in Cannot mix incompatible Qt library:

I just noticed something else: It looks like you are using 64-bit Qt and 64-bit MinGW. Therefore, you must also use the 64-bit MySQL C connector. (Your screenshots show that you've installed 32-bit MySQL)

I missed this passage.

That's OK. mysql-connector-c-6.1.11-winx64 is 64-bit.

After a long time I managed to analyze the .exe on Dependency Walker

Ask Dependency Walker to open qsqlmysql.dll instead of your .exe.

Tamfub · That's OK. `mysql-connector-c-6.1.11-winx64` is 64-bit.

Ask Dependency Walker to open qsqlmysql.dll instead of your .exe.

It seems there are a bunch problems...

What now?

JKSH

@Tamfub said in Cannot mix incompatible Qt library:

It seems there are a bunch problems...

Ignore API-MS-WIN-*.dll and EXT-MS-WIN-.dll. Those are not real problems.

However, libmysql.dll is a real problem. If it is missing, your program cannot load qsqlmysql.dll.

This is what @Christian-Ehrlicher meant by "dependency": qsqlmysql.dll depends on libmysql.dll. You must deploy all of your dependencies.

Tamfub

I finally managed to make it work now: I just copied libmysql.dll from C:\Program Files\MySQL\MySQL Connector C 6.1\lib into the release folder (the same of the .exe) :)

Thank you all so much for your kind patience!