Comment # 13 on bug 1229022 from Fabian Vogt

(In reply to Thomas Rother from comment #11)
> hmmm...
> 
> QT_LOGGING_RULES=*.debug=true keepassxc
> 
> The last lines (I found no way to get the complete debugging output in a
> file):

You can do 

QT_LOGGING_RULES=*.debug=true keepassxc &> logfile