In one embodiment, a device writes messages and corresponding trace-on-failure flags to log files when failure conditions are detected. The device propagates the trace-on-failure flags to headers of the log files. The device forms a file index of the log files that have trace-on-failure flags set in their headers. The device performs, using the file index, a lookup of messages in the log files associated with a particular error context. The device sends data from the lookup to an electronic display.