first of all I'm sorry if there is a guide or something but I didn't found anything for troubleshooting.
Here and there I find some errors in my OTRS System Log and I want to find a cause.
For example I have "OTRS-CGI-41" error with MESSAGE "Need ChannelID or ChannelName!" Then I go to server and check Syslog and find these:
Sep 21 09:58:45 otrs OTRS-CGI-41[7940]: [Error][Kernel::System::CommunicationChannel::ChannelGet][Line:159]: Need ChannelID or ChannelName!
OTRS Sytem Log output:

Linux Server Output:

Another one is:
Error: "OTRS-CGI-41" MESSAGE "FileID, TicketID and ArticleID are needed!"
And Syslog output:
Sep 15 12:29:02 otrs OTRS-CGI-41[29496]: [Error][Kernel::Modules::AgentTicketAttachment::Run][Line:44]: FileID, TicketID and ArticleID are needed!
Sep 15 12:29:23 otrs OTRS-CGI-41[29559]: [Error][Kernel::Modules::AgentTicketAttachment::Run][Line:44]: FileID, TicketID and ArticleID are needed!
OTRS Sytem Log output:

Linux Server Output:

If you can tell me how to troubleshoot this kind of error I would really appreciate it.
Have a nice day,
Mario Dvoršek
OTRS Version: 6.0.27
OS Version: Debian 10 (Buster)
Postgres Vesrsion: PostgreSQL 9.6.19