General Runtime Error

We have a digital asset management (DAM) server that we host for a client. We had a little difficulty in installing the DAM to begin with as we have to employ an Apache VirtualHost in order to pass through 443 requests to 80 and then 8080.

for the most part it works fine except for when trying to download an asset we are faced with a 'General Run Time Error'(see below).

enter image description here

I am convinced that the Virtual Host is causing the issue as the download button will work fine when accessed locally.

Please find the config below:

ServerName localhost DocumentRoot /opt/razuna_tomcat_1_8/tomcat/webapps/razuna ErrorLog /var/log/apache2/error_razuna.log CustomLog /var/log/apache2/razuna.log combined

    # Possible values include: debug, info, notice, wa, error, crit,
    # alert, emerg.
    LogLevel wa

    ProxyRequests Off
    <Proxy *>
            Order deny,allow
            Allow from all
    </Proxy>

    RequestHeader append x_https "on"

    ProxyPreserveHost On
    ProxyTimeout 120
    ProxyVia On
    ProxyPass / http://localhost:8080/
    ProxyPassReverse / http://localhost:8080/

    RewriteEngine On
    RewriteRule ^/(.*.cf[cm]/?.*)$ http://localhost:8080/$1 [P]
    #RewriteRule ^/(*.cf[m]/?.*)$ http://localhost:8080/$1 [P]
    #RewriteRule ^/(.*.cf[cm]?.*)$ http://localhost:8080/$1 [P]

I have tried changing many things, for example editing the regex. However I have had no such luck. If anybody could point me in the right direction it would be very much appreciated. I have tried the forums for the platform but they are less than helpful