Tomcat 8 is not able to handle get request with '|' in query parameters?

This behavior is introduced in all major Tomcat releases:

• Tomcat 7.0.73, 8.0.39, 8.5.7

To fix, do one of the following:

• set relaxedQueryChars to allow this character (recommended, see Lincoln's answer)
• set requestTargetAllow option (deprecated in Tomcat 8.5) (see Jérémie's answer).
• you can downgrade to one of older versions (not recommended - security)

Based on changelog, those changes could affect this behavior:

Tomcat 8.5.3:

Ensure that requests with HTTP method names that are not tokens (as required by RFC 7231) are rejected with a 400 response

Tomcat 8.5.7:

Add additional checks for valid characters to the HTTP request line parsing so invalid request lines are rejected sooner.

The best option (following the standard) - you want to encode your URL on client:

encodeURI("http://localhost:8080/app/handleResponse?msg=name|id|")
> http://localhost:8080/app/handleResponse?msg=name%7Cid%7C

or just query string:

encodeURIComponent("msg=name|id|")
> msg%3Dname%7Cid%7C

It will secure you from other problematic characters (list of invalid URI characters).

Since Tomcat 7.0.76, 8.0.42, 8.5.12 you can define property requestTargetAllow to allow forbiden characters.

Add this line in your catalina.properties

tomcat.util.http.parser.HttpParser.requestTargetAllow=|{}