Unable to run Qt/QML application on Ubuntu 20.04

[Rob005]

Hi,
I'm trying to find a solution for this deployment problem for two days now, without success.

I have a fresh default installation of Ubuntu 20.04.3. I try to run a program, build with Qt 5.15.8 on another Ubuntu 20.04.3 system. I build the piechart example from the tutorial (chapter1-basics).
It runs fine on my developer machine, however, when I try to run it on the other machine, I always end with this error:

Warning: QQml_colorProvider: no color provider has been set!
qrc:/app.qml:62:16: Invalid property assignment: color expected 
             color: "red"
                    ^

I checked the dependencies with ldd, I made a distribution package with CQtDeploy. Always the same error. When I try another program, I get the same warning about the QQml_colorProvider, but I get the error at a different place.

Warning: QQml_colorProvider: no color provider has been set!
qrc:/qml/qml/main.qml:45:5: Connections is not a type 
         Connections
         ^

So the error place/reason seems to be random. I guess something is missing. Any ideas?

[JonB]

@Rob005
Did you Google for Warning: QQml_colorProvider: no color provider has been set and read through those hits?

[Rob005]

@JonB Sure. I did not find anything, beside a bug in Qt 5.15.0-5.15.2 that should have been fixed 6 years ago. And, as I mentioned, it works on my developer machine with the exact same Ubuntu version.