In Console Error Shown:
web.assets_backend.min.js:660 OwlError: Missing template: "web.WebClient" (for component "WebClient")
at owl.App.getTemplate (web.assets_common.min.js:1596:7)
at new ComponentNode (web.assets_common.min.js:1446:133)
at owl.App.makeNode (web.assets_common.min.js:1956:34)
at owl.App.mount (web.assets_common.min.js:1955:17)
at startWebClient (web.assets_backend_prod_only.min.js:6:1171)
You use odoo online or odoo SH sir, probably you should try restart the service, this error is not suppose to happen in those platform.
odoo 16 community
Ok , how you start your odoo, you use config file and run it or you download it from odoo website.
For me, i'm a developer so i always run odoo using odoo.conf file and run via the eclipse IDE