[Solved] HTTP Error 401 Unauthorized When Accessing Zimbra 8.8.9 Shared Calendar and Mailbox

Problem: HTTP Error 401 Unauthorized show on browser when try to access Zimbra 8.8.9 Shared Calendar and Mailbox. It’s most likely the browser either did not send another request with Authorization in response to the 401, or had sent an Authorization which is not using GSS-API / SPNEGO scheme.

Zimbra http error 401 must authenticate

Content Summary

Solution 1: Make sure Browser is Supported
Solution 2: Configure Browser Settings
Reference

Solution 1: Make sure Browser is Supported

The following browsers are supported:
Windows PC: Internet Explorer 6.0 or later, Firefox 3.0 or later, Chrome, Safari
Apple Mac computer: Safari

Solution 2: Configure Browser Settings

For Firefox browser on Windows

Step 1: In address field, type about:config.

Step 2: The warning This might void your warranty is now displayed. Click I’ll be careful, I promise!

Step 3: Search in Filters, type network.n. Enter a comma-delimited list oftrutsed domains or URLs.

Double-click network.negotiate-auth.delegation-uris. Enter http://,https://

Double-click network.negotiate-auth.trusted-uris. Enter http://,https://

Or, to set specific URLs,

Double-click network.negotiate-auth.delegation-uris. Enter the domain addresses. For example,
http://mail1.example.com,https://mail2.example.com

Double-click network.negotiate-auth.trusted-uris. Enter the domain addresses. For example, http://mail1.example.com,https://mail2.example.com

For Internet Explorer, Chrome, and Safari for computers running Windows

Step 1: In these browsers, go to Tools > Internet Options > Security > Local Intranet > Sites. On the Sites dialog make sure all items are checked.

Step 2: Select Advanced. Add the domain server (hostname) URL, both http:// and https://

Step 3: Click OK to close the fle.

Step 4: Go to Tools > Options > Advanced > Security. Locate and check Enable Integrated Windows Authentication.

Step 5: Click OK and close the browser.

For Safari on Apple Mac. No configuration is necessary.

Reference

GitHub Pages: Zimbra Collaboration Administrator Guide version 8.8.6