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Error: Unable to process document while trying to view or download documents using Firefox when using doc isolation or High Risk Isolation with Cloud SWG


Article ID: 256358


Updated On:


Cloud Secure Web Gateway - Cloud SWG Web Isolation Web Isolation Cloud WSS add-on - Full Isolation WSS add-on - Full Isolation WSS add-on - Selective Isolation


While trying to view or download some documents using document isolation or High-Risk Isolation in Cloud SWG, Firefox users experience Error: Unable to process document as below.




On-Premise Web isolation

Cloud Web isolation

(Docisolation / Web Isolation / High risk isolation of Cloud SWG)




The document isolation feature in Web Isolation relies on a set of cookies within the Browser.

If access to these cookies, or the original cookies are lost during the redirection to “” the error “Unable to process document” will be displayed in the Browser.

This is currently known to be caused by one of below issues:

  • The local Browser security & privacy settings are modified so they’re operating in a more secure/strict setting which will block third-party/cross-site tracking cookies.
  • In Microsoft Edge, using IE mode for a compatibility issue for a website.
  • The website will be accessed in IE mode then once accessing a document it is then redirected to “”. This redirection results in the cookies being lost as you exit IE mode. This not a supported use-case.

If your issue is not related to one of the listed issues above, please open a support case for further investigation at






Open firefox. In the address bar type below and hit enter.



Under Privacy and Security, On the right side Under Cookies and Site Data click Manage Exceptions and add below sites.


as well as 



Save changes. Close the browser and reopen. 

Above will work in most cases. However, in some cases you may want to try unchecking Cookies under custom, close browser, reopen and test.

Check Cookies option back again and test to see if the first change is effective.




Click the hamburger icon in the top-right of the browser (Figure 1-1)


  1. Click Settings
  2. Select Privacy & Security in the left-hand side menubar
  3. Under Browser PrivacyEnhanced Tracking Protection
  4. Select Custom and uncheck Cookies (Figure 5-1)
  5. Restart the browser and try to load the page again.