Manually create a guest account in Ubuntu20.04
Ubuntu20.04 has some problem with Guest Session. You can create a guest account with the following procedures
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1. Select "Administration->Users and Groups ->Add" , to create a new "guest" user:
Name: guest
Username: guest
2. Select the "guest" user and go to the "Advance Setting"
1. Under "Advanced" tab, deselect "Disable account" box
2. Click on "Change" Password, and select "Don't ask for password on login" box