Errors after upgrading to Qt 5

Question

I've just upgraded and installed Qt 5 from the official website: https://qt-project.org/downloads Version I chose:

Qt 5.0.1 for Windows 32-bit (MinGW 4.7, 823 MB)

The problem is nothing's no longer working! When I try to run code that perfectly compiled with Qt 4.8, I have 66 errors.

Here are a few examples:

error: invalid use of incomplete type 'class QLabel'
error: forward declaration of 'class QLabel'
error: invalid use of incomplete type 'class QLineEdit'

Very strange errors.

Here is the Compile Output:

mingw32-make: * [debug] Error 2
21:10:34: The process "C:\Qt\Qt5.0.1\Tools\MinGW\bin\mingw32-make.exe" exited with code 2.
Error while building/deploying project SQLWidgetMapper (kit: Desktop Qt 5.0.1 MinGW 32bit)
When executing step 'Make'

Can anyone could give me a clue?

Answer 1

QWidgets have been moved into a separate module. You read the docs, right?

Answer 2

Do you have Qt 4.8 and Qt 5.0 installed at the same time? Check what is in your path environment variable.