Hi Saba,
I duno why your IE starts sending the form data using
(i.e. send form data as query string)...
😞
Is your IE still sending a POST request with additional querystring information, or is it now a pure GET request?
Have you already compared the HTML/JS content for any differences using the one and another browser/access?
Does it also happen on a fresh Windows installations, without additional addons/programs?
You may also press the F12 button in IE and check if some console errors would indicate the problem, or if your problem could be resolved by using a certain IE downlevel mode?
logon cookie is missing" error
You could also try to loosen the cookie-releated security settings, or even puting the site into a different IE security zone to narrow the issue.
Are you using some sort of cookie encryption on your F5?
Deactivate login XSRF protection
XSRF is not an explicit browser functionality. Its more a combination of well established core functionalities. It will make sure you've visited the login site before sending login information. Basically it will track your site usage flow by using reversible but still unpredictable random query strings, form datas and cookie values etc...
about the way IE 11 handles security
Browser security is somewhat complex in these days. I've stopped catching up with all those protection mechanism many years ago... 😉
Cheers, Kai