I get this result with simple NPOI Mapper initialization:
Mapper map = new Mapper("pathtofile\\xxx.xlsx");
=>
ICSharpCode.SharpZipLib.Zip.ZipException: 'Wrong Local header signature: 0x41D'
The file is opened by Excel normally, without password. Moreover, the author of xslx in the metadata is Apache NPOI.
Did somebody have similar error?