NetScaler 401 - Unauthorized: Access is denied due to Invalid Credentials

Error : NetScaler 401 - Unauthorized: Access is denied due to Invalid Credentials

Error on Web Interface :  Event ID 18001 , A communication error occurred while attempting to contact the access gateway authentication service






Background :

NetScaler 10.5
Citrix Web interface server 5.4

Getting above mention error message while access Web interface via NetScaler.

Specify point of Authentication : At Access Gateway.

Checked event viewer  found below mention error.

Resolution.

1-  Check Port 443 open between Webinterface server and VIP.

2-  Install ROOT certificate on Web interface server.

To add certificates to the Trusted Root Certification Authorities store for a local computer

1. Click Start, click Start Search, type mmc, and then press ENTER.
   
2. On the File menu, click Add/Remove Snap-in.
   
3. Under Available snap-ins, click Certificates,and then click Add.
   
4. Under This snap-in will always manage certificates for, click Computer account, and then click Next.
   
5. Click Local computer, and click Finish.
   
6. If you have no more snap-ins to add to the console, click OK.
   
7. In the console tree, double-click Certificates.
   
8. Right-click the Trusted Root Certification Authorities store.
   
9. Click Import to import the certificates and follow the steps in the Certificate Import Wizard.