When using the Export/Import Utility wizard the follow error occurs:
Either the file was not generated by Export or it was corrupted.
If the file was indeed generated by Export, report this an Import bug and submit the export file to customer support.
If you did indeed use export (exp or expdp) to do the export, and you verified your path to the dmp file, the "IMP-00010: not a valid export file, header failed verification" error can be caused by these issues:
Corruption from compression or FTP - If the export file was manipulated it may have become corrupted. The most common cause with FTP is using an ASCII transfer and failing to use the binary flag:
ftp> get -i myexportfile.zip
Importing into an earlier version of Oracle - Dump files change formatting between releases, and it's impossible for any software to recognize a format that was not yet invented. Trying a data pump export (expdp) as input to Oracle 8i will cause the "IMP-00010: not a valid export file, header failed verification" error message.
Test via Oracle's exp.exe and imp.exe:
Look for the "imp" and "exp" executables in your $ORACLE_HOME/bin directory. One can run them interactively, using command line parameters, or using parameter files. Look at the imp/exp parameters before starting. These parameters can be listed by executing the following commands: "exp help=yes" or "imp help=yes".