Qt application cannot run in release

Question

I am using visual studio 2017 and qt 5.12.9 msvc2017_64.

When I compiled the program in "Debug x64", the application worked fine. When I compiled the program in "Release x64", the program can be compiled successfully without any error, but the application cannot be opened and showed nothing (no warning, etc.). I used the windeployqt.

Then, I tried to debug the program in "Release x64" and the visual studio showed me something in the following image.

What should I do to make the program run in release? Thanks for help.

Answer 1

This is because windeployqt will not copy all required dll to release the directory. There is some missing dlls that you need to copy manualy. There is two way to find it out.

1. Use a dependency walker. identify the missing library and copy it to your release directory.
2. Copy the following folder from C:\Qt\Qt5.12\5.12.9\msvc2017_64 to the folder where, your exe is located

plugins
qml
translations
mkspecs

Copy all dll from C:\Qt\Qt5.12\5.12.9\msvc2017_64\bin folder to root folder of your exe.

also create qt.conf filed and all following lines to it

[Paths] 
Prefix=. 
Libraries=lib 
Plugins=plugins 
Qml2Imports=qml 
Translations=translations 
Headers=include 
Documentation=doc 

Now run your exe. after the program runs. try to delete some dll. if the program is using any dll, it will not get deleted. by doing this unused dll will be removed. similar try with qml folder and plugin folder.