==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release):  1.3.1 latest
- Deployed with iRedMail Easy or the downloadable installer? downloadable
- Linux/BSD distribution name and version:  Centos 7.8
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx):Ngninx
- Manage mail accounts with iRedAdmin-Pro? not yet but purchased
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

Greetings,
I am trying to troubleshoot my installation.  I have mostly all the parts working as designed except roundcube.  roundcube reports a blank screen with a 500 error.  screenshot provided. of note, Sogo and iredadmin works as normal.

I followed the instructions to add debugging lines into the roundcube config, and the only lines that appear in /var/log/maillog is the following:

Sep 28 14:01:44 mail roundcube: <omo61khd> [1] SELECT `vars`, `ip`, `changed`, now() AS ts FROM `session` WHERE `sess_id` = 'omo61khdc0pv324v12aohfjh50';
Sep 28 14:01:44 mail roundcube: <omo61khd> [2] UPDATE `session` SET `changed` = now() WHERE `sess_id` = 'omo61khdc0pv324v12aohfjh50';

Here are the lines I have in the roundcube config:

Then add settings below in config/config.inc.php:

// system error reporting, sum of: 1 = log; 4 = show
$config['debug_level'] = 4;

// Log SQL queries
$config['sql_debug'] = true;

// Log IMAP conversation
$config['imap_debug'] = true;

// Log LDAP conversation
$config['ldap_debug'] = true;

// Log SMTP conversation
$config['smtp_debug'] = true;

what am I missing?
Thanks