At the time of writing the default ubuntu installation of Umbrello was version 2.24.3, whilst umbrello built from downloaded sources was 2.31.70.
You can download the umbrello sources from github using the following command
$ git clone https://github.com/KDE/umbrello.git
In order to build on my ubuntu 18.04 setup I first had to install the following packages.
$ sudo apt-get install cmake $ sudo apt-get install -y extra-cmake-modules $ sudo apt install libqt5svg5-dev $ sudo apt-get install libqt5webkit5-dev $ sudo apt install kinit-dev libkf5crash-dev libkf5notifications-dev libkf5notifyconfig-dev libkf5parts-dev libkf5kcmutils-dev libkf5newstuff-dev libkf5coreaddons-dev libkf5i18n-dev libkf5dbusaddons-dev libkf5config-dev -y $ sudo apt install libkf5activities-dev libphonon4qt5-dev -y $ sudo apt install libkf5baloowidgets-dev libkf5filemetadata-dev libkf5kdelibs4support-dev -y $ sudo apt install baloo-kf5-dev -y $ sudo apt install libkf5texteditor-dev -y $ sudo apt install libxml2-dev $ sudo apt install libxslt-dev
You should now be able to build the application using the following command sequence
$ mkdir umbrello/build $ cd umbrello/build $ cmake -DCMAKE_INSTALL_PREFIX=$HOME/umbrello -DBUILD_KF5=1 -DCMAKE_BUILD_TYPE=Debug ../ $ make
and then run with the command
$ umbrello/umbrello5 &