The defaulted documentconverter.properties item 'com.openexchange.documentconverter.minFreeVolumeS izeMB' contained an invalid semicolon at the end of the line. which has been been removed:

# The minimum size in MegaBytes of the volume, the cache is located on, that will not be used by the cache;
# Default value: 1024
-com.openexchange.documentconverter.minFreeVolumeSi zeMB=1024;
+com.openexchange.documentconverter.minFreeVolumeS izeMB=1024