You are missing (in the latter example): RewriteEngine on

I also changed the last line a bit, and got it working with:

   RewriteEngine on
   RewriteCond %{HTTP:Connection} Upgrade [NC]
   RewriteCond %{HTTP:Upgrade} websocket [NC]
   RewriteRule ^/?(.*) "ws://127.0.0.1:30000/$1" [P,L]

But on Apache >= 2.4.47 you can just do:

ProxyPass http://127.0.0.1:30000/ upgrade=websocket

No need to add upgrade=websocket to ProxyPassReverse on the other hand.

References:

• https://httpd.apache.org/docs/2.4/mod/mod_proxy.html#wsupgrade
• https://httpd.apache.org/docs/2.4/mod/mod_proxy.html#upgrade
• https://httpd.apache.org/docs/2.4/mod/mod_proxy.html#protoupgrade
• https://github.com/dani-garcia/vaultwarden/discussions/3598#discussioncomment-6355293