The following error when installing Qt 6.0.0-rc1 packages both when updating from a previous installation and when removing then installing again:

Error during installation process (qt.qt6.600.gcc_64):
The output of 
/home/assam/Qt/6.0.0/gcc_64/bin/qmake -query
is not parseable. Please file a bugreport with this dialog https://bugreports.qt.io.
output: ""

This happens for Desktop Windows/Linux and Android packages.

These versions are detected with errors on QC 4.14-rc1 and cannot be used.

Also, adding a local Qt 6 version build works fine with QC, so this is not a QC issue.