I downloaded the Appimage MuseScoreNightly-201810031236-master-3280e35-x86_64.AppImage and tried to start it under LINUX-Fedora-28. But this fails with issue:

[2658:2701:1004/110034.531353:ERROR:cert_verify_proc_openssl.cc(212)] X509 Verification error unable to get local issuer certificate : 20 : 2 : 4

Wat can I do? Output of mscore check-depends:

ack appears to be installed on this system, so we'll use it.

Package:

MuseScore 3 Portable Nightly Build (3.0.0 unstable)
Unstable Prerelease for Version 3.0.0; Build 097d606

System:

Linux 4.18.11-200.fc28.x86_64 x86_64 GNU/Linux
Fedora release 28 (Twenty Eight)
NAME=Fedora
VERSION="28 (Workstation Edition)"
ID=fedora
VERSION_ID=28
PLATFORM_ID="platform:f28"
PRETTY_NAME="Fedora 28 (Workstation Edition)"
ANSI_COLOR="0;34"
CPE_NAME="cpe:/o:fedoraproject:fedora:28"
HOME_URL="https://fedoraproject.org/"
SUPPORT_URL="https://fedoraproject.org/wiki/Communicating_and_getting_help"
BUG_REPORT_URL="https://bugzilla.redhat.com/"
REDHAT_BUGZILLA_PRODUCT="Fedora"
REDHAT_BUGZILLA_PRODUCT_VERSION=28
REDHAT_SUPPORT_PRODUCT="Fedora"
REDHAT_SUPPORT_PRODUCT_VERSION=28
PRIVACY_POLICY_URL="https://fedoraproject.org/wiki/Legal:PrivacyPolicy"
VARIANT="Workstation Edition"
VARIANT_ID=workstation
Fedora release 28 (Twenty Eight)
Fedora release 28 (Twenty Eight)
cpe:/o:fedoraproject:fedora:28

In package only: 4

libicudata.so.56
libicui18n.so.56
libicuuc.so.56
libporttime.so.0

System only: 135

/lib64/ld-linux-x86-64.so.2
/lib64/libasound.so.2
/lib64/libasyncns.so.0
/lib64/libavahi-client.so.3
/lib64/libavahi-common.so.3
/lib64/libblkid.so.1
/lib64/libbz2.so.1
/lib64/libc.so.6
/lib64/libcap.so.2
/lib64/libcom_err.so.2
/lib64/libcrypt.so.1
/lib64/libcrypto.so.1.1
/lib64/libcups.so.2
/lib64/libdbus-1.so.3
/lib64/libdl.so.2
/lib64/libdrm.so.2
/lib64/libevent-2.1.so.6
/lib64/libexpat.so.1
/lib64/libffi.so.6
/lib64/libFLAC.so.8
/lib64/libfontconfig.so.1
/lib64/libgbm.so.1
/lib64/libgcc_s.so.1
/lib64/libgcrypt.so.20
/lib64/libGL.so.1
/lib64/libGLdispatch.so.0
/lib64/libglib-2.0.so.0
/lib64/libGLX.so.0
/lib64/libgmodule-2.0.so.0
/lib64/libgmp.so.10
/lib64/libgnutls.so.30
/lib64/libgobject-2.0.so.0
/lib64/libgpg-error.so.0
/lib64/libgraphite2.so.3
/lib64/libgsm.so.1
/lib64/libgssapi_krb5.so.2
/lib64/libgthread-2.0.so.0
/lib64/libharfbuzz.so.0
/lib64/libhogweed.so.4
/lib64/libICE.so.6
/lib64/libicudata.so.60
/lib64/libicui18n.so.60
/lib64/libicuuc.so.60
/lib64/libidn2.so.0
/lib64/libjpeg.so.62
/lib64/libk5crypto.so.3
/lib64/libkeyutils.so.1
/lib64/libkrb5.so.3
/lib64/libkrb5support.so.0
/lib64/liblcms2.so.2
/lib64/liblz4.so.1
/lib64/liblzma.so.5
/lib64/libm.so.6
/lib64/libminizip.so.1
/lib64/libmount.so.1
/lib64/libnettle.so.6
/lib64/libogg.so.0
/lib64/libopus.so.0
/lib64/libp11-kit.so.0
/lib64/libpci.so.3
/lib64/libpcre.so.1
/lib64/libpcre2-16.so.0
/lib64/libpcre2-8.so.0
/lib64/libpng16.so.16
/lib64/libpthread.so.0
/lib64/libpulse-mainloop-glib.so.0
/lib64/libpulse.so.0
/lib64/libQt5Bluetooth.so.5
/lib64/libQt5Location.so.5
/lib64/libQt5Nfc.so.5
/lib64/libQt5QuickControls2.so.5
/lib64/libQt5QuickParticles.so.5
/lib64/libQt5QuickTemplates2.so.5
/lib64/libQt5WebSockets.so.5
/lib64/libre2.so.0
/lib64/libresolv.so.2
/lib64/librt.so.1
/lib64/libselinux.so.1
/lib64/libSM.so.6
/lib64/libsnappy.so.1
/lib64/libsndfile.so.1
/lib64/libssl.so.1.1
/lib64/libstdc++.so.6
/lib64/libsystemd.so.0
/lib64/libtasn1.so.6
/lib64/libunistring.so.2
/lib64/libuuid.so.1
/lib64/libvorbis.so.0
/lib64/libvorbisenc.so.2
/lib64/libvorbisfile.so.3
/lib64/libvpx.so.5
/lib64/libwayland-client.so.0
/lib64/libwayland-server.so.0
/lib64/libwebp.so.7
/lib64/libwebpdemux.so.2
/lib64/libwebpmux.so.3
/lib64/libX11-xcb.so.1
/lib64/libX11.so.6
/lib64/libXau.so.6
/lib64/libxcb-dri2.so.0
/lib64/libxcb-glx.so.0
/lib64/libxcb-icccm.so.4
/lib64/libxcb-image.so.0
/lib64/libxcb-keysyms.so.1
/lib64/libxcb-randr.so.0
/lib64/libxcb-render-util.so.0
/lib64/libxcb-render.so.0
/lib64/libxcb-shape.so.0
/lib64/libxcb-shm.so.0
/lib64/libxcb-sync.so.1
/lib64/libxcb-util.so.1
/lib64/libxcb-xfixes.so.0
/lib64/libxcb-xinerama.so.0
/lib64/libxcb-xkb.so.1
/lib64/libxcb.so.1
/lib64/libXcomposite.so.1
/lib64/libXcursor.so.1
/lib64/libXdamage.so.1
/lib64/libXext.so.6
/lib64/libXfixes.so.3
/lib64/libXi.so.6
/lib64/libxkbcommon-x11.so.0
/lib64/libxkbcommon.so.0
/lib64/libXrandr.so.2
/lib64/libXrender.so.1
/lib64/libXss.so.1
/lib64/libXtst.so.6
/lib64/libz.so.1
/usr/lib64/freetype-freeworld/libfreetype.so.6
/usr/lib64/libc.so.6
/usr/lib64/libXau.so.6
/usr/lib64/libxcb-xkb.so.1
/usr/lib64/libxcb.so.1
/usr/lib64/libxkbcommon.so.0
linux-vdso.so.1

Provided by both: 27

/lib64/libEGL.so.1
/lib64/libjack.so.0
/lib64/libportaudio.so.2
/lib64/libportmidi.so.0
/lib64/libQt5Concurrent.so.5
/lib64/libQt5Core.so.5
/lib64/libQt5DBus.so.5
/lib64/libQt5Gui.so.5
/lib64/libQt5Help.so.5
/lib64/libQt5Multimedia.so.5
/lib64/libQt5Network.so.5
/lib64/libQt5OpenGL.so.5
/lib64/libQt5Positioning.so.5
/lib64/libQt5PrintSupport.so.5
/lib64/libQt5Qml.so.5
/lib64/libQt5Quick.so.5
/lib64/libQt5QuickWidgets.so.5
/lib64/libQt5Sql.so.5
/lib64/libQt5Svg.so.5
/lib64/libQt5Test.so.5
/lib64/libQt5WebChannel.so.5
/lib64/libQt5WebEngineCore.so.5
/lib64/libQt5WebEngineWidgets.so.5
/lib64/libQt5Widgets.so.5
/lib64/libQt5XcbQpa.so.5
/lib64/libQt5Xml.so.5
/lib64/libQt5XmlPatterns.so.5

Provided by neither: 15

libQt53DAnimation.so.5
libQt53DCore.so.5
libQt53DExtras.so.5
libQt53DInput.so.5
libQt53DLogic.so.5
libQt53DQuick.so.5
libQt53DQuickAnimation.so.5
libQt53DQuickExtras.so.5
libQt53DQuickInput.so.5
libQt53DQuickRender.so.5
libQt53DQuickScene2D.so.5
libQt53DRender.so.5
libQt5Gamepad.so.5
libQt5Scxml.so.5
libQt5WebView.so.5

Extra: (in package but unlinked. Possibly needed by plugins) 22

libdeclarative_bluetooth.so
libdeclarative_gamepad.so
libdeclarative_nfc.so
libdeclarative_qmlwebsockets.so
libdeclarative_scxml.so
libdeclarative_webview.so
libopenal.so.1
libpng12.so.0
libqjpeg.so
libqmlfolderlistmodelplugin.so
libqmlsettingsplugin.so
libqsvg.so
libqtiff.so
libqtquickextrasflatplugin.so
libqtquickextrasplugin.so
libqtquickscene2dplugin.so
libqtquickscene3dplugin.so
libquick3danimationplugin.so
libquick3dextrasplugin.so
libquick3dinputplugin.so
libquick3dlogicplugin.so
libquick3drenderplugin.so
backes@eule [~/Desktop]: