Help!....

[Lykurg]

Have you cleaned your project before building with the new version of Qt?

[k12yp70n]

I have but it still doesn't work...

[PaceyIV]

try to run qmake and then compile

[k12yp70n]

Tried that as well and it didn't work...

[PaceyIV]

What are you using to develop and compile your project? QtCreator?
Have you check that in Tool\Options\Qt4 is selected the right and valid Qt Version Path?