1.When I tried to upgrade NetScaler from GUI from 11.1 to 12 it does not upgrade and does not even upload the file to the NetScaler.
2.If we try to upgrade the NetScaler from CLI it works.
Found that Libvpath_if_so file is missing on version 12.0 .
However this file is present in version 11.1
Workaround:
copy libvpath_if.so in 12.0 from any 11.1 builds and then tried to upgrade the netscaler from GUI