Startup message re missing security software
Has anyone dealt with or had this problem?
At start up, the loading takes longer than usual and then I get a startup message asking me to connect to wifi to load missing but vital software to deal with a security issue. It warns that until I install the software I won't be able to use my Mac. I'm offered a choice to either introduce my wifi password or to switch off computer. If I switch off the computer and restart, the computer boots okay but I get a message saying that a problem caused the computer to switch off, but nothing more and everything works normally.
If I long-on to wifi, the computer starts to load software but then stops with a message saying that the software load failed, and as before, I switch off and reboot to the same message described above. I updated to Mojave in between the first time this occurred and now the second time.
MacBook Pro 15", macOS 10.14