"Error Code: 84223ADA Unable to tunnel through proxy. HTTP/1.1 403 Forbidden"​ error occurs When Using Tableau Desktop to login to Tableau Server using OAuth

Add an environmental variable NO_PROXY to bypass a proxy server when accessing localhost.

1. Click the search (magnifying glass) icon on the Windows menu.
2. Enter sysdm.cpl to the text box and click the icon.
3. Open the Advanced tab and click Environmental Variables.
4. In the system variables section, click New to add the following environmental variable.
   • Variable: NO_PROXY
   • Value: 127.0.0.1,localhost
5. Click OK to close the window.

Note: Entries of the NO_PROXY environment variable are separated by a comma, not a semi-colon.

If the proxy setting is configured in "Internet Options", you may also need to exclude localhost there.

1. Click the search (magnifying glass) icon on the Windows menu.
2. Enter "Internet Options" to the text box and click the icon.
3. Select Connections > LAN Settings > Advanced.
4. In the Exceptions section,  add the following value.

• 127.0.0.1;localhost

5. Click OK to close the window.

Note: Entries of the Exceptions section are separated by a semi-colon, not a comma.