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Question

Is anyone else getting HTTP 431 Request Header Fields Too Large errors?

  • June 10, 2026
  • 2 replies
  • 12 views
M
Hero (Customer)
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Hi everyone,

We recently upgraded to 25R1 and some users in all our environments (development, test and production) get HTTP error 431 on particular IFS screens.  Only our production environment uses single sign-on, the other environments are username/password based.

A small number of users get the errors on viewing the details of assigned work tasks - those users get the error in all environments but other users do not get the error on the same screen.  Some other users are getting the same error when viewing customer orders, but again it’s not all users.

It was suggested that the LINKERD2_PROXY_OUTBOUND_SERVER_HTTP2_MAX_HEADER_LIST_SIZE and LINKERD2_PROXY_INBOUND_SERVER_HTTP2_MAX_HEADER_LIST_SIZE settings be increased to 65536 but this didn’t make any difference.   It seems possible that the error may be from Cloudflare, as the browser developer log does not show any IFS trace information, but we’re not certain.

Has anyone else seen these errors or have any suggestions on why they are happening?

Thanks,

mmck

2 replies

E
Hero (Employee)
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  • Eugene Wager
  • Hero (Employee)
  • June 11, 2026

​@MMcK,

I searched the IFS Knowledge Base for this error but found no matches.  I then looked on the web and found quite a few hits.  This is a fairly common error and can have a number of causes.

You mentioned above that some users get this error when viewing certain screens.  Other users get the error while viewing other screens.  The websites I visited mentioned that the error occurs when one or more of the following conditions exist for a user and the browser they’ve chosen for accessing IFS Cloud:

  • Browser data or cookies have been corrupted (can be resolved by clearing browser history and cookies)
  • DNS cache has been corrupted (resolved by flushing DNS cache)
  • 3rd party extensions exist (find and remove 3rd party extensions from browser[s] used)
  • Other browser issues (reinstall browser)
  • Existence of redirect loops or repetitive authentication cycles (Fixing the loop usually resolves the issue immediately)

One external website in particular gave detailed instructions on how to do the above mentioned cache-clearing for various popular browsers.  It is accessed at the following URL:

          https://support.vergecloud.com/portal/en/kb/articles/http-error-431#Fixing_this_error_in_Mozilla_Firefox

Since you’ve mentioned how some of your users get these types of errors on some screens, while others get the errors on different screens and, presumably, other users don’t get these errors at all it would make sense to first try these browser-related workarounds first.  

M
Hero (Customer)
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  • MMcK
  • Author
  • Hero (Customer)
  • June 11, 2026

Hi ​@Eugene Wager 

Many thanks for your reply and for taking the time to look into this.

We had also found references to it being a browser issue, and indeed this approach did fix it for some of our users.  I’ll check through the steps described in the URL you provided to see if we’ve missed anything.

However, in other cases, it does appear to be specific to the user account.  For example, when it was first reported by a user that they got the error when viewing their assigned work tasks, we checked our development and test environments by logging on as that user (using userid and password, not single sign-on) but on our own PCs.  In other words, using exactly the same browser.  We got the error when logged on as that user but not when logged on as a different user with the same permission set on the same PC.  I’m guessing IFS would use different cookies for the different sessions?

Thanks again,

mmck

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