I needed to upload the device manager HTML files to a Cisco switch separately because I was low on flash space. You can’t download the HTML separately from Cisco (at least not for the 2950 switch I was upgrading) so I had to make the TAR myself.
So I made up a TAR file with the usual tar -cf command and tried to load it, but got a checksum error:
Loading html.tar PaxHeader/html (unknown file type) -- ignored! %Tar checksum error in ftp://1.2.3.4/html.tar
Turns out that Cisco requires and old format TAR file (compatible with V7 UNIX.) Create the archive with tar -cof and it will work out.