Then, causing the problem to happen, and listing the system’s logs in reverse order of modification time:
ls -lrt /var/log,
tail -n 25on recently modified log files (for reasonable values of 25), and
Read, wonder, think, guess, test, repeat as needed
Causing the problem and then looking at the recently modified logs is common sense but brilliant.
ls -lrt as “list by modification time”.
-t is “sort by modification time” and is easy to remember.