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The library was unable to write a security descriptor header, or to recreate a file's security information. When zipping, this can happen when you have requested that the library write a security descriptor header (see the ExtraHeaders property) but one of the files being zipped is located on a filesystem that does not support security permissions. When unzipping, this can happen when you have requested that the library restore security information stored in the zip file, and the destination filesystem or folder does not support security.
When this warning occurs, you know a file's security information has not been stored or restored. You can choose to either zip or unzip files from or to a filesystem that does support security, or remove the xehSecurity constant from the ExtraHeaders property.