Hi All,
I needed to upgrade my lubuntu system from 32 bit to 64 bit. All the instillation went fine. However when I went to compile code I'm working on through the QT Creator IDE I get an error, presumable because of the up grade. "error while loading shared libraries: libQt5Widgets.so.5: wrong ELF class: ELFCLASS64"
I've Googled this and tried the answers I found, most involve installing " sudo apt-get install ia32-libs" lubuntu reports this doesn't exist, the others mostly use "sudo apt-get install g++-multilib" I've installed but no difference. I'm now reading about downloading .debs and changing system symlinks. I'm really not happy about doing this.
So my questions is how do I fix this without chaging links. Better still doesn't QT have some easy way to swap between 32 and 64 bit, I'd like to work on both.

Thankyou

You should find out that the executable in question is a 32-bit binary or a 64-bit binary. Use file(1)

Thanks solved it, rather than clicking on the build button I went to the project list, right clicked and did full project rebuild. This worked