Hello everybody, i like to ask, if there is reason why  logback/LoggingEvent.java at master · qos-ch/logback  | | | | | | | | | | | logback/LoggingEvent.java at master · qos-ch/logback The reliable, generic, fast and flexible logging framework for Java. - logback/LoggingEvent.java at master · qos... | | | is evaluated during call,  and not "materialised" during log event creation I seen situations when before LoggingEvent was processed, MDC context was reset, and after that MDC data was not present in related log message thank you very much for answer Best regards Peter Kotula