This only applies to Syslog-ng PE servers using RLTP/ALTP for their transport().
After upgrading from Syslog-ng PE version 6.x to Syslog-ng PE version 7.x the service fails to start.
Step 1 - Run the syntax checker as found in the following Knowledge Base (KB) article: https://support.oneidentity.com/syslog-ng-premium-edition/kb/264367/syslog-ng-pe-syntax-check
Step 2 - If the Syntax Check states that the configuration file is failing on the RLTP string than all instances of RLTP within the syslog-ng.conf file need to be replaced with ALTP as the name of the transport protocol has been changed.
Step 3 - Once the RLTP string is substituted with ALTP simply restart the Syslog-ng PE service and it should run without any issues.