Message Oracle RMAN-08135 - some corrupt blocks found during conversion of file string

ERRORsome corrupt blocks found during conversion of file string
CAUSEWhile converting the specified file from one platform to another, some corrupt blocks were discovered in the specified file. Details about the corruption have been written to a server trace file.
ACTIONIf these corrupt blocks are unexpected, you may be able to use Block Media Recovery at the source database to fix the problem, then re-convert the files.