Qt app with MySQL works in developing machine but not in deploying one

[Laureta]

Hi all,

I have my application, developed with Qt 5.4.1, working with MySQL databases in my dev machine (Ubuntu 12.04 32 bit), but when I deploy it to another (Ubuntu 14.04 32 bit), I get the "Driver not loaded" of death.
The destination machine has everything installed, namely:

• MySQL Server 5.5
• MySQL Client 5.5
• MySQL client library (libmysqlclient.so.18.0.0), both at sqldrivers folder and /usr/lib/i386-linux-gnu
• MySQL plugin (libqsqlmysql.so) at sqldrivers folder
• Qt 5.4 libraries, including Qt5Sql.so.5.4.1
• I've even written a script to export the sqldrivers folder path

Seemingly there are no missing dependencies, tested with ldd on both my executable and libqsqlmysql.so. Upon request, I can post the results.
Furthermore, the deploying machine runs PHPmyadmin, so I can access the databases from there.
There is something else that I'm forgetting?

Any suggestion will be appreciated. Thanks in advance.

[anda_skoa]

You can try running your application in an environment that has variable QT_DEBUG_PLUGINS set to 1, making Qt's plugin loading code log what it is doing.

Possible causes can be things like a plugin of a different Qt version being found before the correct one.

Cheers,
_

[Laureta]

You can try running your application in an environment that has variable QT_DEBUG_PLUGINS set to 1

Well, I did that; and the first thing I saw was that I was using a debug plugin.
It's my fault, my laziness, I tried to compile the plugin from Qt Creator without realizing it was in debug mode !!!!
So, I rolled my sleeves up to find the libraries and headers through the file system, and finally I get compiled the plugin from console.

These are the log's relevant parts on my dev machine (working) log.txt
And this is the complete log on the deploy machine log_deploy.txt
Here you can see the application's folder tree on the deploy machine folders_snapshot.png

As you can see, the mysql plugin is not loaded on deploy machine. What might be the cause?

Also, I get a warning when platform plugin is loaded: the plugin <path-to-application-platforms> libqxcb.so uses incompatible Qt library (5.4.1) [release].

In deploy machine, there are Qt 4.8 and Qt 5.1 shared libraries (at /usr/lib/i386-linux-gnu). How can I force to load the libraries distributed with my application, instead of those earlier?

[anda_skoa]

You can set an override search path for the runtime linker using the LD_LIBRARY_PATH environment variable in your start script:

export LD_LIBRARY_PATH=/your/library/path:$LD_LIBRARY_PATH

export LD_LIBRARY_PATH=/your/library/path:$LD_LIBRARY_PATH

To copy to clipboard, switch view to plain text mode 

If you do that in a shell, ldd will also use it, so you can verify which Qt is picked up for your application.

Cheers,
_