Qlik Sense: "Error 400 The http request header is incorrect" randomly when using WebSeal

[Damien_V]

Qlik Sense is returning "Error 400 The http request header is incorrect" when using WebSeal and a virtual proxy with a prefix.

This error can be observed in WebSeal logs.

Environments:

Qlik Sense Enterprise on Windows 

Resolution:

The error is due to a WebSeal behavior. WebSeal sends HEAD requests to the Qlik Sense server without a virtual proxy prefix, which would cause Qlik Sense to return the above error if the DNS name called is not added in the Host white list on the default virtual proxy that doesn't have a prefix.

The way to solve this issue is to either add the DNS name in the host white list on the default virtual proxy or alter the virtual proxy used to not use a prefix. Please see Qlik Sense: How to make a virtual proxy else than Central Proxy the default for details.