Hi, I can not update the system. When I press the update button the update doesn't start. Vers 5.8.5 Linux (x86_64) release 4.9.0-7-amd64
Almost certainly fixed in a newer version; this code path has gotten much more stable. Plasma 5.8 is an LTS version, but I would recommend upgrading to the next LTS version (5.12) if possible.