With Qt 5.11, an error message pops up when launching kontact, which includes all HTML code of the welcome page: File not found: data:text/html;charset=UTF-8,....(lots of HTML code)
reported to Laurent on irc last week. Confirmed.
Indeed it was reported. I still wait that thunbleweed provides qt5.11 :)
FWIW a similar issue in ktp-text-ui was fixed in https://cgit.kde.org/ktp-text-ui.git/commit/?id=5eb5f6841ef7da1cb6e6d1c35de330e74e74b92d
Git commit b78bb7307dab374a5d97aad691c8faf9902db27a by Laurent Montel. Committed on 28/05/2018 at 06:17. Pushed by mlaurent into branch 'Applications/18.04'. Fix Bug 394767 - Error message at start with Qt 5.11 FIXED-IN: 5.8.2 M +3 -0 src/webengine/introductionwebenginepage.cpp https://commits.kde.org/kontact/b78bb7307dab374a5d97aad691c8faf9902db27a