Imported JDB file is not deleted from the incoming folder but extension .err is added:
SEPM setup in a DMZ or an environment which does not have access to symantec.liveupdate.com or LUA.
When importing a file twice that has the same hash\JDB file, the second time the file is imported an error will be generated and the file will be renamed .err
As designed. Make sure that the JDB file being imported is actually a different file. Compare the file hashes if necessary.