I was gone for 4 and 1/2 months. Computer was shut down. I came home, started it up and immediately upgraded to Catilina. I also reset my admin password. Now none of my email accounts work. They still work on my iPhone and iPad but not on the desktop.
Mac mini (Late 2014)
2.8 GHz Dual-Core Intel Core i5
8 GB 1600 MHz DDR3