HTTP 400 - Bad Request errors seen on the application pages after adding ADRUM/javascript agent
HTTP 400 can be cause because of various reasons, and HTTP 400 means there is something in the request which does not adhere to the Server handling this request.
One possible reason could be the length of Headers.
Javascript Agent adds some tracking information in the Request Cookies which will be passed on to the server. Since the request cookies are sent through "Cookie" header, adding adrum information will make a slight increase in the header size.
Various Servers might have a configurations set to limit this length, and if the size of the Cookie header goes beyond this limit, it will reject the error with an HTTP 400.
Solution:
The solution to this is to increase the allowed length of the incoming headers to allow the requests to go through. Various servers will have specific instructions to increase this.
eg:
Apache HTTP Server has the following configuration in httpd.conf which sets this length:
LimitRequestFieldSize
Similarly Apache Tomcat has the following setting in its server configuration(http://tomcat.apache.org/tomcat-5.5-doc/config/http.html):
maxHttpHeaderSize
Adjusting these values to a big enough number so that all the request cookies can fit in should fix the problem.
