User Sign-up Connection Reset Error When Behind Reverse Proxy

I made the changes to lines 973-975 in comprofiler.php as requested. No change in behavior.

I also dug a bit into the live_site variable in configuration.php. In my case it's actually blank. This might be a setting that's set as blank because I set the configuration "Behind Load Balancer" under Proxy in the Global Settings to be on. This actually makes sense because the load balancer/reverse proxy itself will then carry the host name for the site. You can then have one or more web servers behind it, each with its own host name and IP address that will be unique. The load balancer/reverse proxy can also act as an SSL proxy, although you can optionally do SSL all the way through to the individual web servers behind it (which then creates individual SSL tunnels on every interface). When acting as an SSL proxy, only the Internet facing side of the load balancer is SSL encrypted. Connections are passed to individual web servers behind it unencrypted, so the web server thinks everything is in the clear even though the reverse proxy is encrypting on the other side.

If live_site is blank, it may be that's the only thing left that the server can pass to create a valid URL is the IP address of the web server itself.

I'm also upgrading to the current build that was just released. Will keep digging on my side of this too. I'm sure there's a solution. Just have to find it...

I also dug a bit into the live_site variable in configuration.php. In my case it's actually blank.

It's normally supposed to be blank so that's normal.

Within Extensions > Plugins unpublish CBs system plugin then try registering with Joomla's registration form instead of CBs. You've disabled the 3 security checks we perform and it's still having issues so it might be something in Joomla itself since CB first creates the Joomla user then the CB user.

OK - I disabled the CB System Plugin as instructed and enabled system user registration on Joomla itself. The results are interesting...

I first had Administrator approval set as ON for new users. I was then able to get a little farther in creating a user in Joomla from outside of the reverse proxy. The login form was successfully submitted. However, I also had Administrator approval enabled at the Joomla level. When I then tried to approve the validated login, I got the same Connection Reset error as before.

I then set the new user approval in Joomla to Self Approval instead. I was then able to successfully self-register.

But again, this was all at the Joomla level itself, and specifically, when Administrator approval of the account was activated.

So now, I agree there is likely something going on within Joomla itself. But there's also something clearly going on with the form in CB. When I re-enabled the CB System Plugin and tried registering, I was back to the same issue. I'm sure there's a work-around. Just have to find it. I will keep playing with the settings.

Ok, enable CBs system plugin then within User > Manage > Options set the following.

Allow User Registration: No
New User Account Activation: Self
Send Mail to Administrators: No
Captcha: None

This ensures Joomla user store process won't bother checking any of this during CBs Joomla user creation. See if that helps. Seams like something funky going on with the user store when approval is needed. CBs user approval doesn't use Joomla functionality for this so you should be able to keep registration approval on within CB, but if still failing try turning CBs approval and confirmation off in CB > Configuration > Registration.

I think we're at least narrowing it down to something with approval or confirmation process going wonky. Do you've any 3rd party User plugins in Extensions > Plugins? As it could be an extension acting on Joomla user store as well.

There's some old topics below regarding reverse proxy with Joomla. Have you tried any of those solutions? As this could just be a configuration problem.

stackoverflow.com/questions/46133810/using-joomla-on-apache-behind-apache-reverse-proxy

joomla.stackexchange.com/questions/1021/reverse-ssl-proxy-support

stackoverflow.com/questions/48863968/dockerized-joomla-site-with-apache2-as-proxy-problems-loading-js-files

OK, I've changed settings as requested:

Within Users --> Manage --> Options:
Allow User Registration: No
New User Account Activation: Self
Send Mail to Administrators: No
Captcha: None

I then set CB options as requested. The Connect Reset error is back.

I then selectively turned off each option (Admin Approval, Email Checker, Email Confirmation, etc.) and tried again. In every case, I'm still getting the Connection Reset error.

That means, so far, I'm only able to get this to work with the Joomla registration system on and the CB System Plugin disabled, and then only with either no approval or self approval. But, yes, we are definitely narrowing this down and that's encouraging.

Answer about other 3rd party extensions. At this time, no. It's a new install of Joomla 4.1 with Community Builder added as the first thing. I plan to add one or two other extensions that claim to integrate with CB natively, but I have yet to install them. I wanted to get this much working first.

Thanks, also for the additional links on the reverse proxy. I think I have read through them before. That's how I was able to get a valid configuration with HAProxy, including the xforwardfor and cookie based sticky sessions (for when I scale out additional Web servers). The information they contain is great though, and I'd highly recommend these for others configuring reverse proxies as well.

Try editing configuration.php and setting live_site to your full domain. Unfortunately I'm running out of ideas here. I've never needed to setup a reverse proxy for load balancing for Joomla before. Are there any access logs at HAProxy or your server that you can review to see what's going on with that access attempt?