EBS Routine FDPREP cannot read the file report

While users trying to get report from EBS application, they face below issues

Routine FDPREP cannot read the file /u01/ERPPROD/apps/apps_st/appl/xxace/12.0.0/reports/US/test.rep.

Check if the file exists under correct product directory.

Check if the person who started the Concurrent Manager has read privileges on the
Concurrent Manager encountered an error while running Oracle*Report for your concurrent request 3756150.

Solution :

• Check whether that particular report file exists on the same directory.  The file extension should be *.rdf format.
• Check read write permission there for that file.
• If three tiers running in your environment,  try to bounce the application step by step like first application tier and then web tier. Because the concurrent manager process working with application tier.