https://bugs.winehq.org/show_bug.cgi?id=55723
--- Comment #6 from Eric Pouech eric.pouech@gmail.com --- an evolution to regsvr32 has just landed in Wine 8.21 by default (no options), regsvr32 will use graphical message boxes to report errors when run with /s option, it will prints error messages to stderr
so to get back your previous behavior, you should: - run regsvr32 with '/s' option - use stderr (instead of stdout) to capture/display output