You can set MettleCI Workbench to log more verbose diagnostic information by adding a line to your MettleCI config.yml file. This file is typically located at /dm/mci/cofig.yml (on Unix) or C:\dm\mci\cofig.yml (on Windows).
Under the ‘logging:’ section add the following lines
loggers: com.datamigrators.mettle.process.CommandRunner: DEBUG