java.lang.IllegalArgumentException: Invalid character found in the request target. The valid charact

java.lang.IllegalArgumentException: Invalid character found in the request target. 
The valid characters are defined in RFC 7230 and RFC 3986.

This issue is occurring most of the tomcat versions from 7.0.88 onwards.

Solution: (Suggested by Apache team):

Tomcat increased their security and no longer allows raw square brackets in the query string. In the request we have [,] (Square brackets) so the request is not processed by the server.

Add relaxedQueryChars attribute under tag under server.xml (%TOMCAT_HOME%/conf):

<Connector port="80" 
           protocol="HTTP/1.1"
           maxThreads="150"
           connectionTimeout="20000"
           redirectPort="443"
           compression="on"
           compressionMinSize="2048"
           noCompressionUserAgents="gozilla, traviata"
           compressableMimeType="text/html,text/xml"
                                     relaxedQueryChars="[,]"
             />

If application needs more special characters that are not supported by tomcat by default, then add those special characters in relaxedQueryChars attribute, comma-separated as above.