If you are using HTTPS then please use a valid certificate and set that certificate to default.
Also please do not reload the browser which will through you those ajax errors.
Please logout and login with proper credentials and the Ajax forbidden error should be gone.
client denied by server configuration: [authz_core:error] [pid 3445] [client 102.250.7.235:56118] AH01630: client denied by server configuration: /var/www/html/ucp/assets/js/compiled/main/bootstrap-toggle.min.js.map
And this from UCP error log:
2828 2021-09-14 13:45 +02:00: Error: ENOENT: no such file or directory, stat ‘/var/www/html/admin/modules/ucp/node/lib/public/index.html’