Cannot load dll when deploying

[ayanamirei]

I write dbapi.dll myself in eclipse mingw (nothing to do with Qt), in the dll used iconv and winsock functions(static link).

I can load dbapi.dll during Qt developing, both in debug and release setting. When I want to deploy the release version to another desktop (same win7 system), the dll cannot be loaded. Please advise what is wrong. Maybe I need some extra plugins in the release folder because using iconv, winsock functions?

Code is like:

@#ifndef CSHAREDDLL_H
#define CSHAREDDLL_H

#include <QLibrary>

#include "dbapi.h" //the header file of dll

typedef void (*tagSession)(HANDLE const handle);

class CSharedDLL
{
public:
tagSession funSession;

public:
CSharedDLL();
bool load();

private:
QLibrary dbapi;
};

#endif // CSHAREDDLL_H
@

@
#include "cshareddll.h"

CSharedDLL::CSharedDLL():
dbapi("dbapi.dll")
{
}

bool CSharedDLL::load()
{
if (dbapi.load())
{
funSession=(tagSession)dbapi.resolve("runSession");
return funSession;
}
else
return false;
}
@

[hskoglund]

Hi, you could check what DLLs/plugins are actually loaded on your development machine.
Download for example listdlls.exe from sysinternals.com, start your app and then run listdlls <yourappname> to get a list of all the dlls.

[frankiefrank]

I agree with hskoglund - but personally I use Dependency Walker on the deployment machine to see what's broken.

[hskoglund]

Yes Dependency Walker can be useful as well, but it has one great weakness: it does not show the plugins that Qt itself (and not Windows) needs, like qwindows.dll or qwebwiew.dll.

So if you really want a list of all the dlls that needs to be copied to another PC, you need a better tool than Dependency Walker.

[frankiefrank]

@hskoglund I think the last time I used it to diagnose problems with deployment, it was showing me the Qt DLLs I was missing (and in another case I had some libraries expecting Qt 4 DLLs while the deployed project came with the Qt5 versions).

I might be wrong. But anyway, i'll make sure to try out listdlls.exe when I encounter another problem like that.

[JKSH]

[quote author="hskoglund" date="1395828859"]Yes Dependency Walker can be useful as well, but it has one great weakness: it does not show the plugins that Qt itself (and not Windows) needs, like qwindows.dll or qwebwiew.dll.[/quote]If you click "Profile" -> "Start Profiling", it will find those plugins.

[hskoglund]

Indeed, qwindows.dll showed up (!) maybe Dependency Walker isn't so bad after all :-)
(but I still don't like those false warnings, like IESHIMS.DLL missing, that Dependency Walker sometimes shows, or maybe it's just my age showing.)

[ayanamirei]

Just solved. I used iconv functions in my dll, however libiconv-2.dll, not iconv.dll need to copy into the release folder. I download Dep walker and found that. Thanks guys.