The following error is observed in the AEM Dispatcher's log file:
Invalid value for directive DispatcherLogLevel, expected value in range [1-5], actual: 0
This is a known product issue DISP-661.
Due to a change to allow Dispatcher logs to be multi-tenant the log levels were shifted by 1 in 4.2.3
Increment the value of DispatcherLogLevel by 1 to fix issue. i.e. use 1-5 rather than 0-4.
This may cause performance issues or affect your application. As a solution, review the options below.