In the specified redo log file, the second block of the file header contains a sequence number that does match the sequence number that PowerExchange Express CDC for Oracle expects. The file might not be a log file, or it might be a corrupted log file. In an Oracle RAC environment, this message includes the name of the relevant RAC member.
The PowerExchange Express CDC log reader tries to use the alternate log file that has the same sequence number. If this alternate log file does not exist, CDC processing ends
Try to identify the correct redo log file. If you cannot identify it, rematerialize the target. Then cold start the CDC session.