Can't connect nautilus or cadaver webdav clients using dav:// or davs:// protocol

Nextcloud version 18.0.1
O/S Ubuntu 20.04
Apache 2.4.29
PHP version 7.2.24

I am trying to connect nautilus to webdav. It no longer allows use of the https:// protocol and requres a url starting with davs://. Whenever I try to connect to any of:

davs://HOST/remote.php/dav/files/USER/
davs://USER:PASSWORD@HOST/remote.php/dav/files/USER/
davs://HOST:443/remote.php/dav/files/USER/
davs://USER:PASSWORD@HOST:443/remote.php/dav/files/USER/

I get “HTTP Error: unauthorized”.

Nextcloud log gives the following, whether I include credentials in the url or not:
{“reqId”:“6zuopUJhGd3Wa3898AUy”,“level”:0,“time”:“2020-06-05T11:49:54+00:00”,“remoteAddr”:“192.168.2.23”,“user”:"–",“app”:“webdav”,“method”:“OPTIONS”,“url”:"/remote.php/dav/files/USER",“message”:{“Exception”:“Sabre\DAV\Exception\NotAuthenticated”,“Message”:“No public access to this resource., No ‘Authorization: Bearer’ header found. Either the client didn’t send one, or the server is mis-configured, No ‘Authorization: Basic’ header found. Either the client didn’t send one, or the server is misconfigured”,“Code”:0,“Trace”:[{“function”:“beforeMethod”,“class”:“Sabre\DAV\Auth\Plugin”,“type”:"->",“args”:[{“absoluteUrl”:“https://HOST/remote.php/dav/files/USER”,“class”:“Sabre\HTTP\Request”},{“class”:“Sabre\HTTP\Response”}]},{“file”:"/forBackup/www/nextcloud/3rdparty/sabre/event/lib/EventEmitterTrait.php",“line”:105,“function”:“call_user_func_array”,“args”:[[{“autoRequireLogin”:true,“class”:“Sabre\DAV\Auth\Plugin”},“beforeMethod”],[{“absoluteUrl”:“https://HOST/remote.php/dav/files/USER”,“class”:“Sabre\HTTP\Request”},{“class”:“Sabre\HTTP\Response”}]]},{“file”:"/forBackup/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php",“line”:466,“function”:“emit”,“class”:“Sabre\Event\EventEmitter”,“type”:"->",“args”:[“beforeMethod”,[{“absoluteUrl”:“https://HOST/remote.php/dav/files/USER”,“class”:“Sabre\HTTP\Request”},{“class”:“Sabre\HTTP\Response”}]]},{“file”:"/forBackup/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php",“line”:254,“function”:“invokeMethod”,“class”:“Sabre\DAV\Server”,“type”:"->",“args”:[{“absoluteUrl”:“https://HOST/remote.php/dav/files/USER”,“class”:“Sabre\HTTP\Request”},{“class”:“Sabre\HTTP\Response”}]},{“file”:"/forBackup/www/nextcloud/apps/dav/lib/Server.php",“line”:319,“function”:“exec”,“class”:“Sabre\DAV\Server”,“type”:"->",“args”:[]},{“file”:"/forBackup/www/nextcloud/apps/dav/appinfo/v2/remote.php",“line”:35,“function”:“exec”,“class”:“OCA\DAV\Server”,“type”:"->",“args”:[]},{“file”:"/forBackup/www/nextcloud/remote.php",“line”:165,“args”:["/forBackup/www/nextcloud/apps/dav/appinfo/v2/remote.php"],“function”:“require_once”}],“File”:"/forBackup/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Auth/Plugin.php",“Line”:168,“CustomMessage”:"–"},“userAgent”:“gvfs/1.44.1”,“version”:“18.0.1.3”,“id”:“5eda3163293c3”}

{“reqId”:“dTR3GSid3pd6YEnfYo6M”,“level”:0,“time”:“2020-06-05T11:49:57+00:00”,“remoteAddr”:“192.168.2.23”,“user”:"–",“app”:“webdav”,“method”:“OPTIONS”,“url”:"/remote.php/dav/files/USER",“message”:{“Exception”:“OCA\DAV\Connector\Sabre\Exception\PasswordLoginForbidden”,“Message”:"",“Code”:0,“Trace”:[{“file”:"/forBackup/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Auth/Backend/AbstractBasic.php",“line”:105,“function”:“validateUserPass”,“class”:“OCA\DAV\Connector\Sabre\Auth”,“type”:"->",“args”:["*** sensitive parameters replaced ***"]},{“file”:"/forBackup/www/nextcloud/apps/dav/lib/Connector/Sabre/Auth.php",“line”:256,“function”:“check”,“class”:“Sabre\DAV\Auth\Backend\AbstractBasic”,“type”:"->",“args”:[{“absoluteUrl”:“https://HOST/remote.php/dav/files/USER”,“class”:“Sabre\HTTP\Request”},{“class”:“Sabre\HTTP\Response”}]},{“file”:"/forBackup/www/nextcloud/apps/dav/lib/Connector/Sabre/Auth.php",“line”:158,“function”:“auth”,“class”:“OCA\DAV\Connector\Sabre\Auth”,“type”:"->",“args”:[{“absoluteUrl”:“https://HOST/remote.php/dav/files/USER”,“class”:“Sabre\HTTP\Request”},{“class”:“Sabre\HTTP\Response”}]},{“file”:"/forBackup/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Auth/Plugin.php",“line”:201,“function”:“check”,“class”:“OCA\DAV\Connector\Sabre\Auth”,“type”:"->",“args”:[{“absoluteUrl”:“https://HOST/remote.php/dav/files/USER”,“class”:“Sabre\HTTP\Request”},{“class”:“Sabre\HTTP\Response”}]},{“file”:"/forBackup/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Auth/Plugin.php",“line”:150,“function”:“check”,“class”:“Sabre\DAV\Auth\Plugin”,“type”:"->",“args”:[{“absoluteUrl”:“https://HOST/remote.php/dav/files/USER”,“class”:“Sabre\HTTP\Request”},{“class”:“Sabre\HTTP\Response”}]},{“function”:“beforeMethod”,“class”:“Sabre\DAV\Auth\Plugin”,“type”:"->",“args”:[{“absoluteUrl”:“https://HOST/remote.php/dav/files/USER”,“class”:“Sabre\HTTP\Request”},{“class”:“Sabre\HTTP\Response”}]},{“file”:"/forBackup/www/nextcloud/3rdparty/sabre/event/lib/EventEmitterTrait.php",“line”:105,“function”:“call_user_func_array”,“args”:[[{“autoRequireLogin”:true,“class”:“Sabre\DAV\Auth\Plugin”},“beforeMethod”],[{“absoluteUrl”:“https://HOST/remote.php/dav/files/USER”,“class”:“Sabre\HTTP\Request”},{“class”:“Sabre\HTTP\Response”}]]},{“file”:"/forBackup/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php",“line”:466,“function”:“emit”,“class”:“Sabre\Event\EventEmitter”,“type”:"->",“args”:[“beforeMethod”,[{“absoluteUrl”:“https://HOST/remote.php/dav/files/USER”,“class”:“Sabre\HTTP\Request”},{“class”:“Sabre\HTTP\Response”}]]},{“file”:"/forBackup/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php",“line”:254,“function”:“invokeMethod”,“class”:“Sabre\DAV\Server”,“type”:"->",“args”:[{“absoluteUrl”:“https://HOST/remote.php/dav/files/USER”,“class”:“Sabre\HTTP\Request”},{“class”:“Sabre\HTTP\Response”}]},{“file”:"/forBackup/www/nextcloud/apps/dav/lib/Server.php",“line”:319,“function”:“exec”,“class”:“Sabre\DAV\Server”,“type”:"->",“args”:[]},{“file”:"/forBackup/www/nextcloud/apps/dav/appinfo/v2/remote.php",“line”:35,“function”:“exec”,“class”:“OCA\DAV\Server”,“type”:"->",“args”:[]},{“file”:"/forBackup/www/nextcloud/remote.php",“line”:165,“args”:["/forBackup/www/nextcloud/apps/dav/appinfo/v2/remote.php"],“function”:“require_once”}],“File”:"/forBackup/www/nextcloud/apps/dav/lib/Connector/Sabre/Auth.php",“Line”:144,“CustomMessage”:"–"},“userAgent”:“gvfs/1.44.1”,“version”:“18.0.1.3”,“id”:“5eda31665f5e6”}

I know the credentials are correct because I can connect using cadaver command line client using https protocol.

Why do you put :/ after your host ? There’s no :, only the /.

Sorry, copy and paste error when constructing the variants. I only use : after the host if specifying the port.