Cannot mix incompatible Qt library

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!