QSqlDatabase: QMYSQL driver not loaded

Christian Ehrlicher

QSqlDatabase: available drivers: QSQLITE QODBC QPSQL

As you can see there is no MySQL Qt plugin in your Qt installation - so why do you expect that it works?
You have to compile the MySQL Qt plugin by yourself as properly described in the documentation or use another database which is directly supported.

AlexFr

@Christian-Ehrlicher thanks. When I try to run the command you suggested, I get this error:
The ""cmake"" command is either misspelled or
could not be found.

Christian Ehrlicher

@AlexFr said in QSqlDatabase: QMYSQL driver not loaded:

When I try to run the command you suggested, I get this error:

I did not suggest any command.
If you want to compile your plugin, you have to make sure that your development environment is properly set up (which also means cmake is available in your PATH).

AlexFr

@Christian-Ehrlicher thanks for your answer. I compiled the plugin with the command: qt-cmake -G Ninja C:\Qt\6.0.0\Src\qtbase\src\plugins\sqldrivers -DMySQL_INCLUDE_DIR="C:\mysql-8.0.22-winx64\include" -DMySQL_LIBRARY="C:\mysql-8.0.22-winx64\lib\libmysql.lib" -DCMAKE_INSTALL_PREFIX="C:\Qt\6.0.0\mingw81_64"

but still nothing has changed. it compiled without errors, but I still get the same error in Qt creator. Please do you have futher ideas regarding this issue I am facing? I am also researching it online.

SGaist

As I suggested, did you install the plugin ?

AlexFr

@SGaist I tried, but I get an error. the file "mysql.h" is missing from the <MySQL dir>/include/ directory. I installed MySQL smoothly but somehow that file is missing.

hskoglund

Hi, please be careful with your versions of Qt:

you use Qt 5.15.2 for the debug build
(C:/Users/Nelson/Documents/CP/build-DatabaseConn-Desktop_Qt_5_15_2_MSVC2019_64bit-Debug/debug/)
'C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/ as the place where Qt looks for the MySQL plugin
C:\Qt\6.0.0\Src\qtbase\src\plugins\sqldrivers is where you build it from (and installing to C:\Qt\6.0.0\mingw81_64)

Don't know if that's the cause of the problems but it will help to only use one version of Qt for everything :-)

AlexFr

@SGaist I finally have installed it, but the error persists.

"
QSqlDatabase: QMYSQL driver not loaded
QSqlDatabase: available drivers: QSQLITE QODBC QPSQL
"

AlexFr

@hskoglund yeah I fixed that. thanks. but it was not the cause of my woes.

AlexFr

@SGaist the errors I am getting

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("QPSQL")
qt.core.plugin.factoryloader: checking directory path "C:/Users/user/Documents/CP/build-DatabaseConnection-Desktop_Qt_6_4_0_MSVC2019_64bit-Debug/debug/sqldrivers" ...
QSqlDatabase: QMYSQL driver not loaded
QSqlDatabase: available drivers: QSQLITE QODBC QPSQL
No Connection

qt.core.plugin.factoryloader: checking directory path "C:/Qt/6.4.0/msvc2019_64/plugins/accessiblebridge" ...
qt.core.plugin.factoryloader: checking directory path "C:/Users/user/Documents/CP/build-DatabaseConnection-Desktop_Qt_6_4_0_MSVC2019_64bit-Debug/debug/accessiblebridge" ...

any help would be greatly appreciated.

JonB

@AlexFr said in QSqlDatabase: QMYSQL driver not loaded:

QSqlDatabase: QMYSQL driver not loaded
QSqlDatabase: available drivers: QSQLITE QODBC QPSQL

Your output show no sign/mention of finding any QMYSQL plugin anywhere (where it is looking). So what file(s) do you have where for plugins with regard to QMYSQL? It looks like either there is nothing at all, so it cannot even try to load it, or there is some output earlier in the diagnostic relating to QMYSQL which you are not showing.

AlexFr

@JonB in this folder "C:\Qt\6.4.0\mingw_64\plugins\sqldrivers", I have "qsqlmysql.dll" and "qsqlmysql.debug", amongst other files. I built the plugin using:
"
mkdir build-sqldrivers
cd build-sqldrivers

qt-cmake -G Ninja <qt_installation_path>\Src\qtbase\src\plugins\sqldrivers -DCMAKE_INSTALL_PREFIX=<qt_installation_path><platform> -DMySQL_INCLUDE_DIR="C:\mysql-8.0.22-winx64\include" -DMySQL_LIBRARY="C:\mysql-8.0.22-winx64\lib\libmysql.lib"
cmake --build .
cmake --install .
"

JonB

@hskoglund said in QSqlDatabase: QMYSQL driver not loaded:

'C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/ as the place where Qt looks for the MySQL plugin
C:\Qt\6.0.0\Src\qtbase\src\plugins\sqldrivers is where you build it from (and installing to C:\Qt\6.0.0\mingw81_64)

@AlexFr said in QSqlDatabase: QMYSQL driver not loaded:

@JonB in this folder "C:\Qt\6.4.0\mingw_64\plugins\sqldrivers", I have "qsqlmysql.dll" and "qsqlmysql.debug"

Seems to me you have a mix-up/mismatch betwenn these paths, not to mention whether you are using MinGW versus MSVC. Sort out what you are using from where, for sure. That is all I know.

AlexFr

@JonB thanks for the reply. I also have I have "qsqlmysql.dll" and "qsqlmysql.debug" in "C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/" and it still does not work.

JonB

@AlexFr
It's no good just having the files in that directory, you have to have the application looking in that directory to find it/them. I do not not know whether that is happening in your situation.

AlexFr

@JonB thanks for the reply.
this is part of the error message:
"
qt.core.plugin.factoryloader: checking directory path "C:/Qt/6.4.0/msvc2019_64/plugins/accessiblebridge"
"

hskoglund

Hi, you can try building your app in Release mode (not Debug), perhaps the release mode version of the QMySQL plugin you built will be picked up better than the debug version.
Also please include all of the output from QT_DEBUG_PLUGINS, not just a single line...

AlexFr

@hskoglund Hi. Thanks for the answer. I tried that, still I get the same errors. I can post the errors of course.

qt.core.plugin.factoryloader: checking directory path "C:/Qt/6.4.0/msvc2019_64/plugins/platforms" ...
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qdirect2d.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qdirect2d.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"direct2d"
]
},
"archlevel": 1,
"className": "QWindowsDirect2DIntegrationPlugin",
"debug": false,
"version": 394240
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("direct2d")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qdirect2dd.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qdirect2dd.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"direct2d"
]
},
"archlevel": 1,
"className": "QWindowsDirect2DIntegrationPlugin",
"debug": true,
"version": 394240
}

qt.core.plugin.factoryloader: "The plugin 'C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qdirect2dd.dll' uses incompatible Qt library. (Cannot mix debug and release libraries.)"
not a plugin
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qminimal.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qminimal.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"minimal"
]
},
"archlevel": 0,
"className": "QMinimalIntegrationPlugin",
"debug": false,
"version": 394240
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("minimal")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qminimald.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qminimald.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"minimal"
]
},
"archlevel": 0,
"className": "QMinimalIntegrationPlugin",
"debug": true,
"version": 394240
}

qt.core.plugin.factoryloader: "The plugin 'C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qminimald.dll' uses incompatible Qt library. (Cannot mix debug and release libraries.)"
not a plugin
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qoffscreen.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qoffscreen.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"offscreen"
]
},
"archlevel": 0,
"className": "QOffscreenIntegrationPlugin",
"debug": false,
"version": 394240
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("offscreen")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qoffscreend.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qoffscreend.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"offscreen"
]
},
"archlevel": 0,
"className": "QOffscreenIntegrationPlugin",
"debug": true,
"version": 394240
}

qt.core.plugin.factoryloader: "The plugin 'C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qoffscreend.dll' uses incompatible Qt library. (Cannot mix debug and release libraries.)"
not a plugin
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qwindows.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qwindows.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"windows"
]
},
"archlevel": 0,
"className": "QWindowsIntegrationPlugin",
"debug": false,
"version": 394240
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("windows")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qwindowsd.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qwindowsd.dll, metadata=
{
"IID": "org.qt-project.Qt.QPA.QPlatformIntegrationFactoryInterface.5.3",
"MetaData": {
"Keys": [
"windows"
]
},
"archlevel": 0,
"className": "QWindowsIntegrationPlugin",
"debug": true,
"version": 394240
}

qt.core.plugin.factoryloader: "The plugin 'C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qwindowsd.dll' uses incompatible Qt library. (Cannot mix debug and release libraries.)"
not a plugin
qt.core.plugin.factoryloader: checking directory path "C:/Users/user/Documents/CP/build-DatabaseConnection-Desktop_Qt_6_4_0_MSVC2019_64bit-Release/release/platforms" ...
qt.core.library: "C:/Qt/6.4.0/msvc2019_64/plugins/platforms/qwindows.dll" loaded library
qt.core.plugin.factoryloader: checking directory path "C:/Qt/6.4.0/msvc2019_64/plugins/platformthemes" ...
qt.core.plugin.factoryloader: checking directory path "C:/Users/user/Documents/CP/build-DatabaseConnection-Desktop_Qt_6_4_0_MSVC2019_64bit-Release/release/platformthemes" ...
qt.core.plugin.factoryloader: checking directory path "C:/Qt/6.4.0/msvc2019_64/plugins/styles" ...
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/styles/qwindowsvistastyle.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/styles/qwindowsvistastyle.dll, metadata=
{
"IID": "org.qt-project.Qt.QStyleFactoryInterface",
"MetaData": {
"Keys": [
"windowsvista"
]
},
"archlevel": 0,
"className": "QWindowsVistaStylePlugin",
"debug": false,
"version": 394240
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("windowsvista")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/styles/qwindowsvistastyled.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/styles/qwindowsvistastyled.dll, metadata=
{
"IID": "org.qt-project.Qt.QStyleFactoryInterface",
"MetaData": {
"Keys": [
"windowsvista"
]
},
"archlevel": 0,
"className": "QWindowsVistaStylePlugin",
"debug": true,
"version": 394240
}

qt.core.plugin.factoryloader: "The plugin 'C:/Qt/6.4.0/msvc2019_64/plugins/styles/qwindowsvistastyled.dll' uses incompatible Qt library. (Cannot mix debug and release libraries.)"
not a plugin
qt.core.plugin.factoryloader: checking directory path "C:/Users/user/Documents/CP/build-DatabaseConnection-Desktop_Qt_6_4_0_MSVC2019_64bit-Release/release/styles" ...
qt.core.library: "C:/Qt/6.4.0/msvc2019_64/plugins/styles/qwindowsvistastyle.dll" loaded library
qt.core.plugin.factoryloader: checking directory path "C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers" ...
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlite.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlite.dll, metadata=
{
"IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
"MetaData": {
"Keys": [
"QSQLITE"
]
},
"archlevel": 0,
"className": "QSQLiteDriverPlugin",
"debug": false,
"version": 394240
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("QSQLITE")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlited.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlited.dll, metadata=
{
"IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
"MetaData": {
"Keys": [
"QSQLITE"
]
},
"archlevel": 0,
"className": "QSQLiteDriverPlugin",
"debug": true,
"version": 394240
}

qt.core.plugin.factoryloader: "The plugin 'C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlited.dll' uses incompatible Qt library. (Cannot mix debug and release libraries.)"
not a plugin
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlmysql.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlmysql.dll, metadata=
{
"IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
"MetaData": {
"Keys": [
"QMYSQL",
"QMARIADB"
]
},
"archlevel": 2,
"className": "QMYSQLDriverPlugin",
"debug": false,
"version": 394240
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("QMYSQL", "QMARIADB")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlodbc.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlodbc.dll, metadata=
{
"IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
"MetaData": {
"Keys": [
"QODBC"
]
},
"archlevel": 0,
"className": "QODBCDriverPlugin",
"debug": false,
"version": 394240
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("QODBC")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlodbcd.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlodbcd.dll, metadata=
{
"IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
"MetaData": {
"Keys": [
"QODBC"
]
},
"archlevel": 0,
"className": "QODBCDriverPlugin",
"debug": true,
"version": 394240
}

qt.core.plugin.factoryloader: "The plugin 'C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlodbcd.dll' uses incompatible Qt library. (Cannot mix debug and release libraries.)"
not a plugin
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlpsql.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlpsql.dll, metadata=
{
"IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
"MetaData": {
"Keys": [
"QPSQL"
]
},
"archlevel": 0,
"className": "QPSQLDriverPlugin",
"debug": false,
"version": 394240
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList("QPSQL")
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlpsqld.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlpsqld.dll, metadata=
{
"IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
"MetaData": {
"Keys": [
"QPSQL"
]
},
"archlevel": 0,
"className": "QPSQLDriverPlugin",
"debug": true,
"version": 394240
}

qt.core.plugin.factoryloader: "The plugin 'C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlpsqld.dll' uses incompatible Qt library. (Cannot mix debug and release libraries.)"
not a plugin
qt.core.plugin.factoryloader: checking directory path "C:/Users/user/Documents/CP/build-DatabaseConnection-Desktop_Qt_6_4_0_MSVC2019_64bit-Release/release/sqldrivers" ...
qt.core.library: "C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlmysql.dll" cannot load: Cannot load library C:\Qt\6.4.0\msvc2019_64\plugins\sqldrivers\qsqlmysql.dll: Das angegebene Modul wurde nicht gefunden.
qt.core.plugin.loader: QLibraryPrivate::loadPlugin failed on "C:/Qt/6.4.0/msvc2019_64/plugins/sqldrivers/qsqlmysql.dll" : "Cannot load library C:\Qt\6.4.0\msvc2019_64\plugins\sqldrivers\qsqlmysql.dll: Das angegebene Modul wurde nicht gefunden."
QSqlDatabase: QMYSQL driver not loaded
QSqlDatabase: available drivers: QSQLITE QMARIADB QMYSQL QODBC QPSQL
No Connection
qt.core.plugin.factoryloader: checking directory path "C:/Qt/6.4.0/msvc2019_64/plugins/accessiblebridge" ...
qt.core.plugin.factoryloader: looking at "C:/Qt/6.4.0/msvc2019_64/plugins/accessiblebridge/qsqlmysql.dll"
qt.core.plugin.loader: Found metadata in lib C:/Qt/6.4.0/msvc2019_64/plugins/accessiblebridge/qsqlmysql.dll, metadata=
{
"IID": "org.qt-project.Qt.QSqlDriverFactoryInterface",
"MetaData": {
"Keys": [
"QMYSQL",
"QMARIADB"
]
},
"archlevel": 2,
"className": "QMYSQLDriverPlugin",
"debug": false,
"version": 394240
}

qt.core.plugin.factoryloader: Got keys from plugin meta data QList()
qt.core.plugin.factoryloader: checking directory path "C:/Users/user/Documents/CP/build-DatabaseConnection-Desktop_Qt_6_4_0_MSVC2019_64bit-Release/release/accessiblebridge" ...

hskoglund

Hi, the output looks good, only one more step should remain, you need to copy the mysql driver dll to the same folder as where your app .exe file is.

The driver dll file is called libmysql.dll and it should be in the C:\Program Files\MySQL\MySQL Server 8.0\lib (provided that you've installed the 64-bit MySQL Installer 8.0.22)
So if I'm guessing correctly then the copy command is:
copy "C:\Program Files\MySQL\MySQL Server 8.0\lib\libmysql.dll" C:\Users\user\Documents\CP\build-DatabaseConnection-Desktop_Qt_6_4_0_MSVC2019_64bit-Release\release

If you cannot find it (or haven't installed the MyQSL Installer) then there are plenty of alternatives for downloading that libmysql.dll file, for example here

AlexFr

@hskoglund Hi. thanks for the answer. it however did not help. I still get the exact same error as above.

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QSqlDatabase: QMYSQL driver not loaded