Qt 5.2.x, Mac OS 10.9.1: Trying to construct an instance of an invalid type, type id: xxxxxxxxxxxx

[janfaroe]

Hi all. Running my application, I'm seeing errors like

Trying to construct an instance of an invalid type, type id: 67129088
Trying to construct an instance of an invalid type, type id: 895772268
Trying to construct an instance of an invalid type, type id: 661220984
Trying to construct an instance of an invalid type, type id: 795767909
Trying to construct an instance of an invalid type, type id: 811925504
Trying to construct an instance of an invalid type, type id: 875522164
Trying to construct an instance of an invalid type, type id: 173237620
Trying to construct an instance of an invalid type, type id: 694484992
Trying to construct an instance of an invalid type, type id: 67129088
Trying to construct an instance of an invalid type, type id: 895772268
Trying to construct an instance of an invalid type, type id: 661220984
Trying to construct an instance of an invalid type, type id: 795767909
Trying to construct an instance of an invalid type, type id: 811925504
Trying to construct an instance of an invalid type, type id: 875522164
Trying to construct an instance of an invalid type, type id: 173237620
Trying to construct an instance of an invalid type, type id: 694484992

after a while, without any interaction. The application remains responsive, but I can't quit in a normal manner, only force quit. I don't see this behavior when using the accompanying Qt Creator in Qt 5.2.x/5.2.1 nightly; I assume it's using the same builds as the SDK. I did not see this in Mac OS 10.9.0.

Any ideas what the error messages mean and how to fix the problem mentioned? Could this be a Mac OS 10.0.1 issue?

[janfaroe]

This is caused by an incompatibility of QNetworkDiskCache files between Qt4.x.y and 5.x. In other words: If you have cached URLS from a 4.x deployed application and deciding to deploy via 5.x, you have problems. This goes the other way around too.

As a bonus bug, one can also experience complete blocking of previously visited URLs. I was on the verge of insanity figuring that one out. Removing the cache directory solves the problem. A workaround might of course be to use different cache directory names for qt4/qt5 (that's at least the path [sic] I've chosen).

[SGaist]

Hi,

That could be an interesting point to bring to the developer's attention. Maybe a doc note would also be a good idea

[janfaroe]

There's already an entry mentioning this:

https://bugreports.qt-project.org/browse/QTBUG-34498

I added a confirming comment and hit the vote button.