After upgrading NetScaler to build 10.5 56.x from 52.x, unable to log on to NetScaler GUI. The following error is displayed - "invalid Argument".

Log on through NetScaler CLI works without any issues.

This error is displayed because the NetScaler has customization applied on it.

To resolve this issue, run the following command from NetScaler CLI:
set vpn parameter -uitheme default

In order to apply the customization again, complete the following steps:

1. Remove the customtheme.tar.gz from ns_gui_custom folder.

2. Make the UI theme default.

3. Reboot the NetScaler.

4. Put the customtheme.tar.gz back to ns_gui_custom location.

5. Select the Custom UI theme again.

Problem Cause

Custom theme breaks the NetScaler GUI access.