Citrix NetScaler | http/1.1 Internal Server Error 43531

This Internal Server Error 43531 is a very specific error code that is almost exclusively associated with Citrix NetScaler or Citrix Gateway.

You are likely seeing this error when trying to logging into a School Portal, Work Remote Desktop, or a Banking/Corporate website that uses Citrix for security.

It is not a standard error for games like Roblox or Valorant.

What it Means

The server you are trying to reach (the StoreFront) is rejecting your connection request, usually because of a browser mismatch or a “Referer Header” issue.

How to Fix It (As a User)

Since you are likely a user trying to access a site, try these steps in order:

  1. Use “Incognito” or “Private” Mode

    • Open your browser (Chrome/Edge/Safari).

    • Press Ctrl + Shift + N (or Cmd + Shift + N on Mac).

    • Try logging in again. This bypasses the “bad” cookies causing the 43531 error.

  2. Clear Your Browser Cache

    • If Incognito worked, you need to clear your main browser’s data.

    • Go to History > Clear Browsing Data.

    • Select “Cookies and other site data” and “Cached images and files.”

    • Restart the browser and try again.

  3. Try a Different Browser

    • If you are using Chrome, try Firefox or Edge.

    • This error is sometimes triggered by a specific update in Chrome that handles security headers differently than the Citrix server expects.

  4. Are you using a Bookmark?

    • Do not use an old bookmark. The error often happens because the bookmark links to an expired session URL.

    • Type the main website address manually (e.g., remote.company.com) and log in fresh.

Also Read : The Division 2 Mike 01 Error | Easy Fix

If You Are the Administrator (Setting up a Server)

If you are the one hosting this site (e.g., for your CS project), this is a known bug in NetScaler builds (specifically related to the “Referer” header in Session Policies).

  • Fix: You need to update your Session Policy expression.

  • Change: REQ.HTTP.HEADER Referer EXISTS

  • To: HTTP.REQ.HEADER("User-Agent").CONTAINS("CitrixReceiver")

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