Concurrent request logfiles have the below error:
REP-0004: Warning: Unable to open user preference file
The prefs.ora is either missing or non-accessible.
1. No prefs.ora file in HOME directory:
Oracle Reports will look into the user's HOME directory for the prefs.ora preferences file. If a prefs.ora file does not exist in your HOME directory, you can copy the prefs.ora file that came with the Oracle Tools.