article Qlik Sense Enterprise on Windows: HTTP Header size restriction in Official Support Articles

Qlik Sense Enterprise on Windows: HTTP Header size restriction

Andre_Sostizzo — Tue, 31 Mar 2026 09:59:49 GMT

SAML authentication fails with the following error:

HTTP Error 400. The size of the request headers is too long.

The entire return code looks as such:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN""http://www.w3.org/TR/html4/strict.dtd">
<HTML><HEAD><TITLE>Bad Request</TITLE>
<META HTTP-EQUIV="Content-Type" Content="text/html; charset=us-ascii"></HEAD>
<BODY><h2>Bad Request - Request Too Long</h2>
<hr><p>HTTP Error 400. The size of the request headers is too long.</p>
</BODY></HTML>

Environment

, any version

Windows and Qlik Sense have a limitation on HTTP Header sizes. The maximum header length is set at 16 KB by default.

Resolution

We recommend you investigate the impact on other programs on the machine, as changing these settings is a system-wide change.

Steps to be applied on the Qlik Sense Server:

Open the Windows Registry Editor with Administrative Permissions.
Create (or locate and change) the following keys and configure them with the desired value:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\HTTP\Parameters\

Create DWord 32
Name = MaxFieldLength
Decimal = 65536

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\HTTP\Parameters\

Create DWord 32
Name = MaxRequestBytes
Decimal = 16777216
Save
Restart the Server
Open the Qlik Sense Management Console
Open the Proxy used and navigate to the Settings of the Proxy
In the Advanced section, input the desired Max header size (bytes)

The HTTP header length can be up to 64 KB.

For more information, see:

Re: Qlik Sense HTTP Header size restriction

Ken_T — Wed, 28 Jul 2021 13:03:11 GMT

We do not see this key in our Feb 2021 version of Qlik Sense. Is this still valid for Feb 2021 and up?

If so, does the key need to be added?

Re: Qlik Sense HTTP Header size restriction

Ken_T — Wed, 28 Jul 2021 13:35:15 GMT

looks like the key needs to be added manually, per Microsoft.

related to this, can this issue also manifest with a 500 error, instead of the 400 error?

We are seeing 500 error for many users with large number of groups, giving a larger header size.
However, users with small number of groups are not seeing any errors and the SAML works fine for them.

is there any issue with the number of groups that could cause a 500 error instead of a 400 error?

Re: Qlik Sense HTTP Header size restriction

Sonja_Bauernfeind — Wed, 28 Jul 2021 13:53:04 GMT

Hello @Ken_T

This is a little too complex to troubleshoot with you (or brainstorm) in an article - we'll need an SME for this and I'd suggest logging a ticket if you haven't already done so.

We try to add as much information as we can to our articles to assist in deeper investigations, but sometimes the right question hasn't been asked yet.

-Sonja

Re: Qlik Sense HTTP Header size restriction

Ken_T — Tue, 03 Aug 2021 17:49:37 GMT

We have tested and proven that we get an HTTP 500 error with SAML when the user has too many groups. This is a close cousin to this error documented on this page, but different. We were getting all the group information in an attribute, memberof. We had to do work with our SAML team to set up a new attribute, that got a smaller set of groups, in a new attribute, in order to workaround this problem.

it appears that Qlik has a limit on the number of groups, we only saw this 500 error when the user was a member of many groups. Users with smaller number of groups, had no error at all and everything worked fine.

This would benefit users, if this error and root cause could be confirmed by Qlik Support and documented. The 500 error is not very informative and we did not see anything in the logs that helped determine the root cause either. it took a while to figure out and find a workaround.

Re: Qlik Sense HTTP Header size restriction

Damien_V — Mon, 09 Aug 2021 08:46:59 GMT

Hello @Ken_T

I believe your issue is rather related to https://community.qlik.com/t5/Knowledge/Qlik-Sense-quot-Qlik-Sense-G3-Broker-API-quot-error-on-the-hub/ta-p/1711832

To be precise, this is the total length of all groups and not the number of groups itself. Less groups with very long group names would cause the same issue.

That header size can be set as per the above article in C:\Program Files\Qlik\Sense\ServiceDispatcher\service.conf

Re: Qlik Sense HTTP Header size restriction

Ken_T — Mon, 09 Aug 2021 13:38:58 GMT

Hi @Damien_V , no, I do not think it is the same issue. the error returned are different, and the workarounds for the total header size (with the 400 error) do not affect this issue with too many groups (the generic 500 error). we tested this and established the root cause of the 500 error was the number of groups. The other workarounds we found, including the one in this article, for the header too large issue which gives a 400 error had no effect on the situation we were facing at all. @Sonja_Bauernfeind thanks for your help as always, unfortunately Qlik Support will usually see SAML in the ticket and not assist at all usually, and suggest that professional services be engaged. even if it seems there may be a defect/feature at play.

I do not think we tested the MaxHttpHeaderSize setting but we did try the registry entry listed in this article.

Re: Qlik Sense HTTP Header size restriction

Damien_V — Mon, 09 Aug 2021 13:51:00 GMT

Hi @Ken_T

Actually for the article I sent, the error was different in different versions (the article probably needs a refresh), in some versions it was "Broker API G3", in some other versions it was an error 500 on any of the Dispatcher service endpoint (/api/v1/language or any other /api/v1/... endpoints, this can be verified in the "network" tab in the browser devtools)

Re: Qlik Sense HTTP Header size restriction

ggijben — Wed, 14 Jun 2023 18:47:17 GMT

This article mentions that the HTTP header length can reach a maximum of 64kb. However, in the QMC (Proxy), a message indicates that the maximum header size is 131072 bytes, which is equivalent to 128kb.

Can someone clarify this ambiguity?

Re: Qlik Sense HTTP Header size restriction

Sonja_Bauernfeind — Mon, 19 Jun 2023 13:24:52 GMT

Hello @ggijben

I'll look into this for you. The documentation we have still references 64kb as well (not only this article), so it may be that we will need case to have this run through RnD. But I will check first to see what I can do without a ticket.

All the best,
Sonja

Re: Qlik Sense HTTP Header size restriction

Sonja_Bauernfeind — Thu, 22 Jun 2023 07:49:02 GMT

Hello @ggijben No ticket is required!

This difference comes from the management console allowing a value it shouldn't. I've reported this as a defect: QB-20272.

All the best,
Sonja