QT example executables won't run, missing QT5Cored.dll

c++, qt

Solution

To run it outside of Qt Creator, you have two choices:

- Copy the missing DLLs to the directory where the executable resides. For example if `analogclock.exe` is in `c:\examples`, then copy `C:\Qt\5.4\mingw491_32\bin\Qt5Cored.dll` and other required DLLs to `c:\examples`. You may need to copy plugins files too.

- Add `C:\Qt\5.4\mingw491_32\bin` to the `PATH` environment variable.

There are some ways to copy the missing DLLs:

1. Use Windows Deployment Tool (windeployqt.exe) to copy required files

- Open Command Prompt in one of the following way:

- If you use MSVC as compiler, open the correct Visual Studio Command Prompt. For example for VS2013 32-bit, click `Start -> Microsoft Visual Studio 2013 -> Visual Studio Tools -> VS2013 x86 Native Tools Command Prompt`. This will open a Command Prompt with the `VCINSTALLDIR` environment variable correctly set. `windeployqt.exe` requires this environment variable to copy the correct Visual C++ redistributable executable.

- If you use MinGW, just open a Command Prompt.

Add Qt binary path and optionally `g++.exe` path to PATH environment variable. If your executable is 32-bit, add the 32-bit Qt binary path, eg: `c:\Qt\5.4\msvc2013\bin`. If your executable is 64-bit, add the 64-bit Qt binary path, eg: `c:\Qt\5.4\msvc2013_64\bin`. `windeployqt.exe` will copy DLLs from this directory, so it is important that you don't set 32-bit Qt binary path for a 64-bit executable, vice versa. You need to add `g++.exe` path too if you use MinGW, windeployqt will copy lib*.dll from there.

; Example path for MSVC 32-bit
PATH=c:\Qt\5.4\msvc2013\bin;%PATH%

; Example path for MinGW 32-bit, g++.exe is in C:\Qt\Tools\mingw491_32\bin
PATH=C:\Qt\5.4\mingw491_32\bin;C:\Qt\Tools\mingw491_32\bin;%PATH%  

Run `windeployqt.exe` with your executable file as argument. Eg:

windeployqt.exe C:\Qt\Examples\Qt-5.4\widgets\richtext\build-calendar-Desktop_Qt_5_4_0_MSVC2013_32bit-Debug\debug\calendar.exe

Check the output for error or warning. The following is an output without error and warning:

2. Manually copy the DLLs

You must copy the correct DLLs (32-bit or 64-bit). Use a tool like Process Explorer to find the correct DLL paths:

- Run the application from Qt Creator / Visual Studio.

- Open Process Explorer.

- In Process Explorer

- Click the executable, for example `calendar.exe`

- Press `Ctrl+D` to show loaded DLLs in the lower panel. The equivalent menu is `View -> Lower Panel View -> DLLs`

- In the lower panel, click the `Path` column to sort by path.

- Copy the DLLs to the directory where the executable resides. For example in the following picture. The DLLs are from C:\Qt\5.4\msvc2013\bin.

- If your executable uses something like `c:\Qt\5.4\msvc2013\plugins\platforms\qwindowsd.dll`. It should be copied too. But copy from the `platforms` directory, not `plugins`. Let's say `calendar.exe`'s full path is `c:\examples\calendar.exe`, then `qwindowsd.dll` should be copied to `c:\examples\platforms\qwindows.dll`, not `c:\examples\plugins\platforms\qwindows.dll`.

You need to copy C++ runtime library too. If you are using mingw, you may need to copy `libgcc_s_dw2-1.dll`, `libstdc++-6.dll`. `libwinpthread-1.dll` etc too. Check in Process Explorer to be sure. If you are using MSVC, you need to deploy the runtime (Eg: `msvcp120.dll`, `msvcr120.dll`). At the end, your directory structure is something like this:

c:\examples\calendar.exe
c:\examples\Qt5Cored.dll
c:\examples\Qt5Widgetsd.dll
c:\examples\Qt5Guid.dll
c:\examples\icudt53.dll
c:\examples\icuin53.dll
c:\examples\icuuc53.dll
c:\examples\libgcc_s_dw2-1.dll   (if using mingw)
c:\examples\libstdc++-6.dll      (if using mingw)
c:\examples\libwinpthread-1.dll  (if using mingw)
c:\examples\platforms\qwindowsd.dll

Problem

Original source