Error when opening Qlik in a non-incognito browser or not clearing the cookies

[cluengo]

We recently started encountering the error "Request header fields too large" when opening Qlik. However, the error disappears when we use an incognito browser or clear our cookies. Is this expected behavior? We're running Qlik Sense on a Windows server. Thanks!

[henrikalmen]

No, that's not expected behaviour. Perhaps this support article will help you: https://community.qlik.com/t5/Official-Support-Articles/Error-431-when-trying-to-access-the-Qlik-Sen... 

[janyf]

Qlik changed something in november release. 
We have same problem with one of our customers. They have qlik accessible through subdomain of their website. We found out that problem is that standard qlik cookie is appended by stuff from main website. 
In past this does not cause issues, but now it causes bug as your described. 

Solution is as Henrik pointed enlarge header size in capabilities and proxy in qmc. 

Here is steps. 
https://community.qlik.com/t5/Official-Support-Articles/Qlik-Sense-Client-Managed-Adjust-the-MaxHttp... 

There is also another guide, where you are changing settings in registry editor of server , this need reboot of server , but will also help. 

Or if you have control over your main website , you could set cookies to not leak to qlik subdomain (if you have this setup). 

[Ray_Strother]

Hello,

Please review the below article links.

1. https://community.qlik.com/t5/Official-Support-Articles/Error-431-when-trying-to-access-the-Qlik-Sen...

2. https://community.qlik.com/t5/Official-Support-Articles/Qlik-Sense-HTTP-Header-size-restriction/ta-p...