The following MD5 checksum error is displayed while upgrading XenServer on NetScaler SDX:
"MD5 checksum failed on the file /var/mps/xen_images/XenServer-6.1-install-cd.iso"

Complete the following steps to resolve this issue:

1. Go to NetScaler ADC download page. 
   Note: You must be logged on to view the download files.

2. Click to expand the desired NetScaler version.

3. Click Service Delivery Appliances.

4. Click a desired SDX version. For example - SDX Release 10.1 Build 128.8.

5. Expand Additional Components and you will see the XenServer installation file which has a special sha256 checksum. 

Problem Cause

The wrong version of the file is downloaded.