ASP.net MVC Culture Info in a Cookie - asp.net-mvc

Question

I have just come across a rather strange issue and I really can't understand why this is happening ...
I have a rather simple, MVC website based on .NET Framework 4.7.2. I'm keeping 2 Resource files (resx) for a couple of languages. So far so good. What I do is keeping the selected Culture into a Cookie with the CultureInfo (en-US & el-GR). In my development maching, using IISExpress, everything is running like a charm! The cookie is being updated as expected and of course the value switching can be seen from the browser debugging.
Using Application_BeginRequest() from Global.asax I can recover the selected culture:
protected void Application_BeginRequest(object sender, EventArgs e)
{
string culture = "el-GR";
var langCookie = Request.Cookies["SiderLangCookie"];
if (langCookie != null)
culture = langCookie.Value;
else
{
culture = "el-GR";
HttpCookie cookie = new HttpCookie("SiderLangCookie", culture)
{
HttpOnly = true,
Expires = DateTime.Now.AddMonths(6)
};
Response.AddHeader("Set-Cookie", "SameSite=Strict;Secure");
Response.AppendCookie(cookie);
}
Thread.CurrentThread.CurrentCulture = CultureInfo.GetCultureInfo(culture);
Thread.CurrentThread.CurrentUICulture = CultureInfo.GetCultureInfo(culture);
}
And later on, if the user chooses to do so, he/she may change the culture from an anchor button:
<a class="socials-item" href="javascript:SwitchLanguage();" title="Language"><i class="fa fa-flag" aria-hidden="true"></i></a>
which is calling a javascript function for an AJAX POST request to the Controller action:
function SwitchLanguage() {
$.ajax({
url: '#Url.Action("SwitchLanguage", "Home")',
method: 'POST',
success: function (response) {
if (response.result == "OK") {
toastr.success("#Resource.LanguageSwitchSuccess", "SUCCESS");
setTimeout(function () { window.location.reload(); }, 2500);
}
},
error: function () {
toastr.error("#Resource.LanguageSwitchError", "ERROR");
}
});
}
and this is my action:
[HttpPost]
public ActionResult SwitchLanguage()
{
string lang = "en-US";
var langCookie = Request.Cookies["SiderLangCookie"];
if (langCookie == null)
{
langCookie = new HttpCookie("SiderLangCookie", lang)
{
HttpOnly = true,
Expires = DateTime.Now.AddMonths(6),
};
Response.AddHeader("Set-Cookie", "SameSite=Strict;Secure");
Response.AppendCookie(langCookie);
}
else
{
lang = langCookie.Value;
if (lang == "en-US")
lang = "el-GR";
else
lang = "en-US";
langCookie.Value = lang;
Response.AddHeader("Set-Cookie", "SameSite=Strict;Secure");
Response.SetCookie(langCookie);
}
Thread.CurrentThread.CurrentCulture = CultureInfo.GetCultureInfo(lang);
Thread.CurrentThread.CurrentUICulture = CultureInfo.GetCultureInfo(lang);
return Json(new { result = "OK" }, JsonRequestBehavior.AllowGet);
}
For some reason, when I deploy the website (Publishing to a folder and uploading to the Host), even though the Action code is executing successfully (no exceptions and errors whatsoever), the cookie is no longer updating the value to either el-GR or en-US. It just sticks to the first value it got when first created.
Does anyone have the slightest clue why is this happening?
Thanks in advance.

Answer 1

Cookies issues usually appears if you do not have correct setup the relative sessions on web.config.
Check the domain that is correct setup with out the www. - if you use the www. then check that all calls done from www.
<httpCookies domain="yourdomain.com" httpOnlyCookies="true" requireSSL="true"/>
The domain property also exist on forms and on roleManager

Answer 2

Ok, I managed to figure out the situation. Many many thanks to Thomas Ardal who wrote this article:
[The ultimate guide to secure cookies with web.config in .NET][1]
[1]: https://blog.elmah.io/the-ultimate-guide-to-secure-cookies-with-web-config-in-net/
It seems that the latest changes regarding Cookie management by the browsers are more restrictive than anticipated.
Incorporating the rewrite rule, Thomas proposed, did the trick.
Now the Cookie value seems to be changing as expected.
Thanks