[SOLVED]Unable to deploy under Linux (MySQL plugin issue)

Leonardo

Hi. I don't think you need to rebuild it. I think you just need to copy the missing dependencies to your executable's directory.

SGaist

Hi and welcome to devnet,

Which qmake did you call to rebuild the plugin ?

Also, depending on the distro you are targeting, shouldn't you rather make a package for it ?

HPCTECH

@Leonardo I tried to copy all the dependencies manually but unfortunately it didn't fix my issue.

Any way, I deleted all the dependencies then called ldd as following but I still get QMYSQL driver not loaded

ldd AndroidMysqlClient 	linux-vdso.so.1 =>  (0x00007fffbb5fe000)
	libQt5Widgets.so.5 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libQt5Widgets.so.5 (0x00007fc849dfd000)
	libQt5Sql.so.5 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libQt5Sql.so.5 (0x00007fc849bbc000)
	libQt5Core.so.5 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libQt5Core.so.5 (0x00007fc849476000)
	libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fc849149000)
	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fc848f32000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fc848b6d000)
	libQt5Gui.so.5 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libQt5Gui.so.5 (0x00007fc84835b000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fc84813c000)
	libgobject-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 (0x00007fc847eeb000)
	libgthread-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007fc847ce9000)
	librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007fc847ae0000)
	libglib-2.0.so.0 => /lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007fc8477d8000)
	libXext.so.6 => /usr/lib/x86_64-linux-gnu/libXext.so.6 (0x00007fc8475c6000)
	libX11.so.6 => /usr/lib/x86_64-linux-gnu/libX11.so.6 (0x00007fc847290000)
	libGL.so.1 => /usr/lib/x86_64-linux-gnu/mesa/libGL.so.1 (0x00007fc84702a000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fc846d24000)
	libicui18n.so.54 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libicui18n.so.54 (0x00007fc8468b5000)
	libicuuc.so.54 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libicuuc.so.54 (0x00007fc846507000)
	libicudata.so.54 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libicudata.so.54 (0x00007fc844add000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fc8448d8000)
	/lib64/ld-linux-x86-64.so.2 (0x00007fc84a67e000)
	libffi.so.6 => /usr/lib/x86_64-linux-gnu/libffi.so.6 (0x00007fc8446d0000)
	libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007fc844491000)
	libxcb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb.so.1 (0x00007fc844272000)
	libglapi.so.0 => /usr/lib/x86_64-linux-gnu/libglapi.so.0 (0x00007fc84404b000)
	libXdamage.so.1 => /usr/lib/x86_64-linux-gnu/libXdamage.so.1 (0x00007fc843e47000)
	libXfixes.so.3 => /usr/lib/x86_64-linux-gnu/libXfixes.so.3 (0x00007fc843c41000)
	libX11-xcb.so.1 => /usr/lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007fc843a3f000)
	libxcb-glx.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-glx.so.0 (0x00007fc843827000)
	libxcb-dri2.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-dri2.so.0 (0x00007fc843622000)
	libxcb-dri3.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-dri3.so.0 (0x00007fc84341f000)
	libxcb-present.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-present.so.0 (0x00007fc84321b000)
	libxcb-sync.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-sync.so.1 (0x00007fc843015000)
	libxshmfence.so.1 => /usr/lib/x86_64-linux-gnu/libxshmfence.so.1 (0x00007fc842e13000)
	libXxf86vm.so.1 => /usr/lib/x86_64-linux-gnu/libXxf86vm.so.1 (0x00007fc842c0c000)
	libdrm.so.2 => /usr/lib/x86_64-linux-gnu/libdrm.so.2 (0x00007fc842a00000)
	libXau.so.6 => /usr/lib/x86_64-linux-gnu/libXau.so.6 (0x00007fc8427fb000)
	libXdmcp.so.6 => /usr/lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007fc8425f5000)
hpctech-work@hpctech-work ~/Snippets/C++ Qt/build-AndroidMysqlClient-Desktop_Qt_5_5_1_GCC_64bit-Debug $

HPCTECH

@SGaist Thanks for reply

Which qmake did you call to rebuild the plugin ?

below you can find full log of my building attempt:

hpctech-work@hpctech-work ~/.Qt/5.5/Src/qtbase/src/sql/drivers/mysql $ /home/hpctech-work/.Qt/5.5/gcc_64/bin/qmake /home/hpctech-work/.Qt/5.5/Src/qtbase/src/sql/drivers/mysql/qsql_mysql.pri
hpctech-work@hpctech-work ~/.Qt/5.5/Src/qtbase/src/sql/drivers/mysql $ make
g++ -c -pipe -I/usr/include/mysql -O2 -fno-exceptions -Wall -W -D_REENTRANT -fPIC -DQT_NO_MTDEV -DQT_NO_LIBUDEV -DQT_NO_TSLIB -DQT_NO_LIBINPUT -DQT_NO_EXCEPTIONS -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_CORE_LIB -I. -I/home/hpctech-work/.Qt/5.5/gcc_64/include -I/home/hpctech-work/.Qt/5.5/gcc_64/include/QtGui -I/home/hpctech-work/.Qt/5.5/gcc_64/include/QtCore -I.moc -I/usr/include/libdrm -I../../../../mkspecs/linux-g++ -o .obj/qsql_mysql.o qsql_mysql.cpp
qsql_mysql.cpp:36:40: fatal error: QtSql/private/qsqldriver_p.h: No such file or directory
 #include <QtSql/private/qsqldriver_p.h>
                                        ^
compilation terminated.
make: *** [.obj/qsql_mysql.o] Error 1
hpctech-work@hpctech-work ~/.Qt/5.5/Src/qtbase/src/sql/drivers/mysql $

HPCTECH

Guys may I get some help.

Depending on this doc (it seems outdated) I made another attempt to build QMySQLPlugin but unfortunately I got same result.

hpctech-work@hpctech-work ~/.Qt/5.5/Src/qtbase/src/sql/drivers/mysql $ ~/.Qt/5.5/gcc_64/bin/qmake "INCLUDEPATH+=/usr/local/include" "LIBS+=-L/usr/local/lib -lmysqlclient_r" mysql.pro
Cannot find file: mysql.pro.
hpctech-work@hpctech-work ~/.Qt/5.5/Src/qtbase/src/sql/drivers/mysql $ ~/.Qt/5.5/gcc_64/bin/qmake "INCLUDEPATH+=/usr/local/include" "LIBS+=-L/usr/local/lib -lmysqlclient_r" mysql.pri
Cannot find file: mysql.pri.
hpctech-work@hpctech-work ~/.Qt/5.5/Src/qtbase/src/sql/drivers/mysql $ ~/.Qt/5.5/gcc_64/bin/qmake "INCLUDEPATH+=/usr/local/include" "LIBS+=-L/usr/local/lib -lmysqlclient_r" qsql_mysql.pri
hpctech-work@hpctech-work ~/.Qt/5.5/Src/qtbase/src/sql/drivers/mysql $ make
g++ -c -pipe -I/usr/include/mysql -O2 -fno-exceptions -Wall -W -D_REENTRANT -fPIC -DQT_NO_MTDEV -DQT_NO_LIBUDEV -DQT_NO_TSLIB -DQT_NO_LIBINPUT -DQT_NO_EXCEPTIONS -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_CORE_LIB -I. -I/usr/local/include -I/home/hpctech-work/.Qt/5.5/gcc_64/include -I/home/hpctech-work/.Qt/5.5/gcc_64/include/QtGui -I/home/hpctech-work/.Qt/5.5/gcc_64/include/QtCore -I.moc -I/usr/include/libdrm -I../../../../mkspecs/linux-g++ -o .obj/qsql_mysql.o qsql_mysql.cpp
qsql_mysql.cpp:36:40: fatal error: QtSql/private/qsqldriver_p.h: No such file or directory
 #include <QtSql/private/qsqldriver_p.h>
                                        ^
compilation terminated.
make: *** [.obj/qsql_mysql.o] Error 1
hpctech-work@hpctech-work ~/.Qt/5.5/Src/qtbase/src/sql/drivers/mysql $

BTW: I tried to fix my issue by following same steps of this post but it reached to dead end :(

Some of my system:

hpctech-work@hpctech-work ~ $ locate libqsqlmysql.so
/usr/lib/x86_64-linux-gnu/qt5/plugins/sqldrivers/libqsqlmysql.so
hpctech-work@hpctech-work ~ $ locate libmysqlclient.so
/usr/lib/x86_64-linux-gnu/libmysqlclient.so
/usr/lib/x86_64-linux-gnu/libmysqlclient.so.18
/usr/lib/x86_64-linux-gnu/libmysqlclient.so.18.0.0
hpctech-work@hpctech-work ~ $ locate libmysqlclient_r.so
/usr/lib/x86_64-linux-gnu/libmysqlclient_r.so
/usr/lib/x86_64-linux-gnu/libmysqlclient_r.so.18
/usr/lib/x86_64-linux-gnu/libmysqlclient_r.so.18.0.0
hpctech-work@hpctech-work ~ $

HPCTECH

BTW, qsqldriver_p.h isn't missing but qsql_mysql.pri couldn't find it

hpctech-work@hpctech-work ~ $ ls ~/.Qt/5.5/Src/qtbase/include/QtSql/5.5.1/QtSql/private/
qsqlcachedresult_p.h  qsqldriver_p.h  qsql_mysql_p.h      qsql_oci_p.h   qsql_psql_p.h       qsqlresult_p.h    qsql_sqlite_p.h     qsql_tds_p.h
qsql_db2_p.h          qsql_ibase_p.h  qsqlnulldriver_p.h  qsql_odbc_p.h  qsqlquerymodel_p.h  qsql_sqlite2_p.h  qsqltablemodel_p.h
hpctech-work@hpctech-work ~ $

SGaist

You're in the wrong folder, it's src/plugins/sqldrivers/mysql

HPCTECH

@SGaist said:

You're in the wrong folder, it's src/plugins/sqldrivers/mysql

Yep. I found the right path which is ~/.Qt/5.5/Src/qtbase/plugins/sqldrivers thanks @SGaist

Any way, my problem still exists & became much worst because it occurs too when I run my app using Qt Creator although I re-built libqsqlmysql.so successfully!

hpctech-work@hpctech-work ~/.Qt/5.5/Src/qtbase/src/plugins/sqldrivers/mysql $ ~/.Qt/5.5/gcc_64/bin/qmake "INCLUDEPATH+=/usr/local/include" "LIBS+=-L/usr/local/lib -lmysqlclient_r" mysql.pro
hpctech-work@hpctech-work ~/.Qt/5.5/Src/qtbase/src/plugins/sqldrivers/mysql $ make
rm -f libqsqlmysql.so
g++ -Wl,--no-undefined -Wl,-O1 -Wl,--enable-new-dtags -Wl,-rpath,/home/hpctech-work/.Qt/5.5/gcc_64 -Wl,-rpath,/home/hpctech-work/.Qt/5.5/gcc_64 -Wl,-rpath,/home/hpctech-work/.Qt/5.5/gcc_64/lib -shared -o libqsqlmysql.so .obj/main.o .obj/qsql_mysql.o .obj/moc_qsql_mysql_p.o  -L/usr/local/lib -rdynamic -L/usr/lib64/mysql -lmysqlclient_r -lz -lcrypt -lnsl -lm -lssl -lcrypto -L/home/hpctech-work/.Qt/5.5/gcc_64/lib -lQt5Sql -lQt5Core -lpthread  
mv -f libqsqlmysql.so ../../../../plugins/sqldrivers/ 
hpctech-work@hpctech-work ~/.Qt/5.5/Src/qtbase/src/plugins/sqldrivers/mysql $ cd ../../../../plugins/sqldrivers/
hpctech-work@hpctech-work ~/.Qt/5.5/Src/qtbase/plugins/sqldrivers $ cp libqsqlmysql.so /home/hpctech-work/.Qt/5.5/gcc_64/plugins/sqldrivers/
hpctech-work@hpctech-work ~/.Qt/5.5/Src/qtbase/plugins/sqldrivers $ ldd ~/.Qt/5.5/gcc_64/plugins/sqldrivers/libqsqlmysql.so 
	linux-vdso.so.1 =>  (0x00007fffcf1fe000)
	libmysqlclient.so.18 => /usr/lib/x86_64-linux-gnu/libmysqlclient.so.18 (0x00007fe886488000)
	libQt5Sql.so.5 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libQt5Sql.so.5 (0x00007fe886247000)
	libQt5Core.so.5 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libQt5Core.so.5 (0x00007fe885b01000)
	libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007fe8857fd000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007fe885438000)
	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007fe88521e000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007fe88501a000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007fe884dfc000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007fe884af5000)
	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007fe8848df000)
	libicui18n.so.54 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libicui18n.so.54 (0x00007fe884471000)
	libicuuc.so.54 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libicuuc.so.54 (0x00007fe8840c2000)
	libicudata.so.54 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libicudata.so.54 (0x00007fe882698000)
	libgthread-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007fe882496000)
	librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007fe88228d000)
	libglib-2.0.so.0 => /lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007fe881f85000)
	/lib64/ld-linux-x86-64.so.2 (0x00007fe886bfe000)
	libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007fe881d46000)
hpctech-work@hpctech-work ~/.Qt/5.5/Src/qtbase/plugins/sqldrivers $

HPCTECH

As attempting for fixing this issue. I copied sqldrivers folder to app path but it didn't fix the issue because my app & Qt Creator still show QMYSQL driver not loaded

hpctech-work@hpctech-work ~/Snippets/C++ Qt/build-AndroidMysqlClient-Desktop_Qt_5_5_1_GCC_64bit-Debug $ ls -Rl
.:
total 2116
-rwxr-xr-x 1 hpctech-work hpctech-work 667329 Oct 24 08:34 AndroidMysqlClient
-rw-r--r-- 1 hpctech-work hpctech-work 822872 Oct 24 08:34 dialog.o
-rw-r--r-- 1 hpctech-work hpctech-work 247752 Oct 24 08:34 main.o
-rw-r--r-- 1 hpctech-work hpctech-work  58758 Oct 24 08:34 Makefile
-rw-r--r-- 1 hpctech-work hpctech-work   3306 Oct 24 08:34 moc_dialog.cpp
-rw-r--r-- 1 hpctech-work hpctech-work 291496 Oct 24 08:34 moc_dialog.o
drwxr-xr-x 2 hpctech-work hpctech-work   4096 Oct 24 08:46 sqldrivers
-rw-r--r-- 1 hpctech-work hpctech-work   2995 Oct 24 08:34 ui_dialog.h

./sqldrivers:
total 1020
-rwxr-xr-x 1 hpctech-work hpctech-work 838064 Oct 13 11:14 libqsqlite.so
-rwxr-xr-x 1 hpctech-work hpctech-work  98222 Oct 24 08:12 libqsqlmysql.so
-rwxr-xr-x 1 hpctech-work hpctech-work  79248 Oct 13 11:14 libqsqlpsql.so
hpctech-work@hpctech-work ~/Snippets/C++ Qt/build-AndroidMysqlClient-Desktop_Qt_5_5_1_GCC_64bit-Debug $ ldd AndroidMysqlClient 
	linux-vdso.so.1 =>  (0x00007fff6b3fe000)
	libQt5Widgets.so.5 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libQt5Widgets.so.5 (0x00007f71dd56e000)
	libQt5Sql.so.5 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libQt5Sql.so.5 (0x00007f71dd32d000)
	libQt5Core.so.5 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libQt5Core.so.5 (0x00007f71dcbe7000)
	libstdc++.so.6 => /usr/lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007f71dc8b9000)
	libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f71dc6a2000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f71dc2dd000)
	libQt5Gui.so.5 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libQt5Gui.so.5 (0x00007f71dbacb000)
	libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f71db8ac000)
	libgobject-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 (0x00007f71db65b000)
	libgthread-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007f71db459000)
	librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f71db250000)
	libglib-2.0.so.0 => /lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007f71daf48000)
	libXext.so.6 => /usr/lib/x86_64-linux-gnu/libXext.so.6 (0x00007f71dad36000)
	libX11.so.6 => /usr/lib/x86_64-linux-gnu/libX11.so.6 (0x00007f71daa00000)
	libGL.so.1 => /usr/lib/x86_64-linux-gnu/mesa/libGL.so.1 (0x00007f71da79a000)
	libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f71da494000)
	libicui18n.so.54 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libicui18n.so.54 (0x00007f71da025000)
	libicuuc.so.54 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libicuuc.so.54 (0x00007f71d9c77000)
	libicudata.so.54 => /home/hpctech-work/.Qt/5.5/gcc_64/lib/libicudata.so.54 (0x00007f71d824d000)
	libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f71d8048000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f71dddef000)
	libffi.so.6 => /usr/lib/x86_64-linux-gnu/libffi.so.6 (0x00007f71d7e40000)
	libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007f71d7c01000)
	libxcb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb.so.1 (0x00007f71d79e2000)
	libglapi.so.0 => /usr/lib/x86_64-linux-gnu/libglapi.so.0 (0x00007f71d77bb000)
	libXdamage.so.1 => /usr/lib/x86_64-linux-gnu/libXdamage.so.1 (0x00007f71d75b7000)
	libXfixes.so.3 => /usr/lib/x86_64-linux-gnu/libXfixes.so.3 (0x00007f71d73b1000)
	libX11-xcb.so.1 => /usr/lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007f71d71af000)
	libxcb-glx.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-glx.so.0 (0x00007f71d6f97000)
	libxcb-dri2.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-dri2.so.0 (0x00007f71d6d92000)
	libxcb-dri3.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-dri3.so.0 (0x00007f71d6b8f000)
	libxcb-present.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-present.so.0 (0x00007f71d698b000)
	libxcb-sync.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-sync.so.1 (0x00007f71d6785000)
	libxshmfence.so.1 => /usr/lib/x86_64-linux-gnu/libxshmfence.so.1 (0x00007f71d6583000)
	libXxf86vm.so.1 => /usr/lib/x86_64-linux-gnu/libXxf86vm.so.1 (0x00007f71d637c000)
	libdrm.so.2 => /usr/lib/x86_64-linux-gnu/libdrm.so.2 (0x00007f71d6170000)
	libXau.so.6 => /usr/lib/x86_64-linux-gnu/libXau.so.6 (0x00007f71d5f6b000)
	libXdmcp.so.6 => /usr/lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007f71d5d65000)
hpctech-work@hpctech-work ~/Snippets/C++ Qt/build-AndroidMysqlClient-Desktop_Qt_5_5_1_GCC_64bit-Debug $

SGaist

Moving the folder beside your application won't help on linux unless you modify the environment a bit so they can be found. But since you have the sql plugin built and in place, you should print the value of lastError to get more information.

HPCTECH

@SGaist

@SGaist said:

Moving the folder beside your application won't help on linux unless you modify the environment a bit so they can be found.

How can I do that?

But since you have the sql plugin built and in place, you should print the value of lastError to get more information.

Print out the result of lastError() but I got nothing more than I get before see the snippet please:

void Dialog::on_pushButton_connect_clicked()
{
    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
    db.setHostName("localhost");
    db.setDatabaseName("mysql");
    db.setUserName("root");
    db.setPassword("root");
    if (!db.open()) {
        ui->plainTextEdit_log->setPlainText(db.lastError().text());
        ui->plainTextEdit_log->appendPlainText(QString("----\nPaths\n----\n%1").arg(qApp->libraryPaths().join("\n")));
    }
}

The result was:

Driver not loaded Driver not loaded
----
Paths
----
/home/hpctech-work/.Qt/5.5/gcc_64/plugins
/home/hpctech-work/Snippets/C++ Qt/build-AndroidMysqlClient-Desktop_Qt_5_5_1_GCC_64bit-Debug

SGaist

Can you run your application QT_DEBUG_PLUGINS set to 1 ? That should give some additional pointers as to why it doesn't load the plugin.

HPCTECH

@SGaist said:

Can you run your application QT_DEBUG_PLUGINS set to 1 ? That should give some additional pointers as to why it doesn't load the plugin.

The result of plugin debug: https://pastebin.kde.org/ps06nig6x

SGaist

You are missing the openssl libraries

HPCTECH

@SGaist said:

You are missing the openssl libraries

It's not related to my issue because it points to "libqsqlmysql.so" which is not needed in my application (the needed one is libqsqlmysql.so)

Any way, I fixed the problem (thanks to Hamish Moffatt from Qt mailing list) by removing "libqsqlmysql.so" (the old plugin original file shipped by Qt Installer) outside sqldrivers folder