Sorry for being late - there is a 'error reporting' sticky for RotK in bug forum. But the principle remains the same for most mods:

Quote Originally Posted by Gigantus View Post
  1. General = Due to a drain on resources the error log has been set to 'error' - the lowest setting. To find errors that do not leave a comprehensive message, kindly set your log to 'trace' and then compress and attach the error log after a crash.
  2. Finding the log = it will be in the ...\Medieval II Total War\logs folder
  3. Setting the log to trace = open Configuration.cfg (in the Three Kingdoms main folder) with Notepad. In the [log] section, remove the hash ( # ) in front of the trace line and add a hash in front of the error line, save. The log will become rather big, but compressing will reduce it to approximately 5-10% of it's original size
  4. Submitting the log = compress the log with a utility like 7Zip and then attach it or upload to a service provider and copy the link in your post

Code:
[log] 
to = logs/M2TW.system.log.txt 
level = * trace
#level = * error