Importing log files using DSpace 3.1 appears to be broken.
I was having problems with importing old log files using the command-line utilities, with a null pointer exception related to metadataStorageInfo. It looks like this is related to JIRA
DS-1248. The StatisticsImporter class is grabbing metadataStorageInfo, which is null because it’s no longer being initialized in SolrLogger.
As a temporary measure I just commented out the offending code in StatisticsImporter and recompiled, but a quick search revealed other classes that still contain refs to metadataStorageInfo.