Launcher & panel are solid so..

[Doug McMahon]

See this -
sudo glib-compile-schemas /usr/share/glib-2.0/schemas
[sudo] password for doug:
override for key “transparency-mode” in schema “org.gnome.shell.extensions.dash-to-dock” in override file “/usr/share/glib-2.0/schemas/10_ubuntu-dock.gschema.override” is not in the list of valid choices; ignoring override for this key.

ProblemType: Bug
DistroRelease: Ubuntu 19.04
Package: gnome-shell-extension-ubuntu-dock 64ubuntu5
ProcVersionSignature: Ubuntu 5.0.0-7.8-generic 5.0.0
Uname: Linux 5.0.0-7-generic x86_64
ApportVersion: 2.20.10-0ubuntu23
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Tue Mar 12 19:50:54 2019
InstallationDate: Installed on 2019-03-12 (0 days ago)
InstallationMedia: Ubuntu 19.04 "Disco Dingo" - Alpha amd64 (20190312)
PackageArchitecture: all
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-shell-extension-ubuntu-dock
UpgradeStatus: No upgrade log present (probably fresh install)

[Doug McMahon (mc3man)]

A g-s update made panel solid so at least on same page. The override file needs editing..

[Guilhem Lettron (guilhem-fr)]

Panel transparency option have been removed in this commit: https://gitlab.gnome.org/GNOME/gnome-shell/commit/9cfb51c106abd1f96012bf39f3d329cf060035cf
and ADAPTIVE option here: https://github.com/micheleg/dash-to-dock/commit/8ccc7d2d55e1b425be605ff3d29052f5a43994ec

So override have to be edited