New Users Can't Sign Up Due to Internal Server Errors?

I’m having some from a pretty much new installation of the snap version of Nextcloud. I haven’t done anything aside for install a few apps and configure things like the splash screen, but I’m experiencing a few errors of this style:

I suspect that these errors are preventing new users from signing up as well using the ‘registration’ app.

Nextcloud version (eg, 12.0.2): 17.0.5
Operating system and version (eg, Ubuntu 17.04): Ubuntu Server 18.04LTS
Apache or nginx version (eg, Apache 2.4.25): (Whatever is bundled with the snap version)
PHP version (eg, 7.1): (Whatever is bundled with the snap version)

The issue you are facing:

Is this the first time you’ve seen this error? (Y/N): y

Steps to replicate it:

1 Try to register as new user from internet
2 go to register page
3 enter email and press register
4 get internal server error

The output of your Nextcloud log in Admin > Logging:

There is this connection issue which I suspect was from a new user trying to register: It says that it cannot establish a connection with localhost and I get it every time that I try to register using private mode on a browser from an external IP address.

I’m not using Apache (as far as I know), and I access the webpage via direct ip addrees in the URL bar. I know that this works because I get the splash screen. I’m using a self-signed SSL certificate, but I don’t think that this should matter.

How can I resolve these issues and what is happening?

[index] Error: Swift_TransportException: Connection could not be established with host 127.0.0.1 [Connection refused #111] at <<closure>>

 0. /snap/nextcloud/20007/htdocs/3rdparty/swiftmailer/swiftmailer/lib/classes/Swift/Transport/StreamBuffer.php line 58
    Swift_Transport_StreamBuffer->establishSocketConnection()
 1. /snap/nextcloud/20007/htdocs/3rdparty/swiftmailer/swiftmailer/lib/classes/Swift/Transport/AbstractSmtpTransport.php line 143
    Swift_Transport_StreamBuffer->initialize({protocol: "",ho ... ]})
 2. /snap/nextcloud/20007/htdocs/3rdparty/swiftmailer/swiftmailer/lib/classes/Swift/Mailer.php line 65
    Swift_Transport_AbstractSmtpTransport->start()
 3. /snap/nextcloud/20007/htdocs/lib/private/Mail/Mailer.php line 180
    Swift_Mailer->send(Swift_Message {}, [])
 4. /var/snap/nextcloud/20007/nextcloud/extra-apps/registration/service/mailservice.php line 101
    OC\Mail\Mailer->send(OC\Mail\Message {})
 5. /var/snap/nextcloud/20007/nextcloud/extra-apps/registration/controller/registercontroller.php line 87
    OCA\Registration\Service\MailService->sendTokenByMail(OCA\Registration\Db\Registration {id: 3})
 6. /snap/nextcloud/20007/htdocs/lib/private/AppFramework/Http/Dispatcher.php line 170
    OCA\Registration\Controller\RegisterController->validateEmail("giwolax278@lagsixtome.com")
 7. /snap/nextcloud/20007/htdocs/lib/private/AppFramework/Http/Dispatcher.php line 99
    OC\AppFramework\Http\Dispatcher->executeController(OCA\Registration ... {}, "validateEmail")
 8. /snap/nextcloud/20007/htdocs/lib/private/AppFramework/App.php line 126
    OC\AppFramework\Http\Dispatcher->dispatch(OCA\Registration ... {}, "validateEmail")
 9. /snap/nextcloud/20007/htdocs/lib/private/AppFramework/Routing/RouteActionHandler.php line 47
    OC\AppFramework\App::main("OCA\\Registrati ... r", "validateEmail", OC\AppFramework\ ... {}, {_route: "regist ... "})
10. <<closure>>
    OC\AppFramework\Routing\RouteActionHandler->__invoke({_route: "regist ... "})
11. /snap/nextcloud/20007/htdocs/lib/private/Route/Router.php line 297
    undefinedundefinedcall_user_func(OC\AppFramework\ ... {}, {_route: "regist ... "})
12. /snap/nextcloud/20007/htdocs/lib/base.php line 997
    OC\Route\Router->match("/apps/registration/")
13. /snap/nextcloud/20007/htdocs/index.php line 42
    OC::handleRequest()

POST /index.php/apps/registration/
from 89.187.161.67 at 2020-04-13T17:34:33+00:00

This error surrounds the breeze dark theme app:

[lib] Error: ResourceLocator can not find a web root (root: /var/snap/nextcloud/20007/nextcloud/extra-apps/breezedark, file: index.php/css/breezedark/e4f6-3c2d-server.css?v=19e49e0b57b3dc1feff49928efb5ccc9, webRoot: , throw: true)

GET /index.php/settings/admin/logging
from 192.168.1.1 by sarah at 2020-04-13T17:29:20+00:00