Statistics utility finishes with incorrect output in stderr:
# /usr/local/psa/admin/bin/statistics --calculate-one --domain-name domain.tld
DEBUG [panel] Processing service node #1[local]
, stderr: Executing logs preparation...
WARNING during statistics_collector execution: : Executing logs preparation...
Issue is reported to Service Team with ID PPPM-1963 and fixed in Plesk12.0.18 #MU34
It has been fixed in scope of Parallels Plesk 12.0.18 MU#34. Please install Plesk updates.