Roundcube Gives a White Page
When you attempt to log in to Roundcube and receive a blank "white page," it is typically due to a communication failure between the Roundcube web application and the LxRoot Control Panel API.
How Roundcube Configuration Works
Roundcube does not store static IMAP/SMTP settings. Instead, it makes a callback to your Control Panel URL to dynamically determine the correct mail settings for the specific mailbox being accessed. For this handshake to succeed, two conditions must be met:
Valid SSL Certificate
Your Control Panel must have a valid, trusted SSL certificate (either a Let's Encrypt auto-SSL or a custom certificate). If the certificate is expired or self-signed, the PHP container will reject the connection for security reasons, resulting in a white page.
Internal Accessibility
The PHP container running Roundcube must be able to resolve and reach the Control Panel URL. If your firewall or DNS settings block the server from "talking to itself" via its public URL, the lookup will fail.
Check your Control Panel's SSL status first. If you recently changed the Control Panel URL or IP, ensure the new records have propagated and that the Let's Encrypt certificate has been successfully re-issued for the new domain.