docs: error messages (#2889)

* docs: add error messages

* docs: add error messages

* docs: add error messages screen shots

* Update docs/docs/manuals/error-messages.md

Co-authored-by: Florian Forster <florian@caos.ch>

* docs: add error messages screen shots

* docs: rename file

Co-authored-by: Florian Forster <florian@caos.ch>

docs/docs/manuals/troubleshooting.md

@@ -0,0 +1,28 @@
+---
+title: Troubleshoot
+---
+
+You will find some possible error messages here, what the problem is and what some possible solutions can be.
+
+## User Agent does not correspond
+
+This error appeared for some users as soon as they were redirected to the login page of ZITADEL.
+ZITADEL uses some cookies to identify the browser/user agent of the user, so it is able to store the active user sessions. By blocking the cookies the functions of ZITADEL will be affected.
+
+We only found this issue with iPhone users, and it was dependent on the settings of the device.
+
+### Solution
+
+Go to the settings of the app Safari and check in the "Experimental WebKit Features" if SameSite strict enforcement (ITP) is disabled
+Also check if "block all cookies" is active. If so please disable this setting.
+
+To make sure, that your new settings will trigger, please restart your mobile phone and try it again.
+
+**Settings > Safari > Advanced > Experimental Features > disable: „SameSite strict enforcement (ITP)“**
+
+![Same Site Strict Enforvement](/img/manuals/errors/same-site-strict.png)
+
+**Settings > Safari > disable: "Block All cookies"** 
+![Block all cookies](/img/manuals/errors/block-cookies.png)
+
+Do you still face this issue? Please contact us, and we will help you find out what the problem is.

docs/sidebars.js

@@ -242,6 +242,7 @@ module.exports = {
             items: ['manuals/user-register', 'manuals/user-login', 'manuals/user-passwordless', 'manuals/user-password', 'manuals/user-factors', 'manuals/user-email', 'manuals/user-phone', 'manuals/user-social-login',],
             collapsed: false,
         },
+        'manuals/troubleshooting'
     ],
     legal: [
         'legal/introduction',