"Invalid character found in the request target" logs and causing a bad request state

Note: please note that Liferay has renamed its Liferay Experience Could offerings to Liferay SaaS (formerly LXC) and Liferay PaaS (formerly LXC-SM).

Issue

• Trying to access an URL that contains special characters the page fails to load showing a HTTP Status 400 - Bad Request Tomcat page.
• Also the following logs can be found:

java.lang.IllegalArgumentException: Invalid character found in the request target [/<CLIENT URL CONTAINING SPECIAL CHARACTER>]. 
The valid characters are defined in RFC 7230 and RFC 3986 at
 org.apache.coyote.http11.Http11InputBuffer.parseRequestLine(Http11InputBuffer.java:494) at
 org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:271) at
 org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65) at
 org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:891) at 
 org.apache.tomcat.util.net.Nio2Endpoint$SocketProcessor.doRun(Nio2Endpoint.java:1703) at
 org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) at
 org.apache.tomcat.util.net.AbstractEndpoint.processSocket(AbstractEndpoint.java:1190) at
 org.apache.tomcat.util.net.Nio2Endpoint$Nio2SocketWrapper$2.completed(Nio2Endpoint.java:634) at
 org.apache.tomcat.util.net.Nio2Endpoint$Nio2SocketWrapper$2.completed(Nio2Endpoint.java:612) at
 java.base/sun.nio.ch.Invoker.invokeUnchecked(Invoker.java:127) at
 java.base/sun.nio.ch.Invoker$2.run(Invoker.java:219) at
 java.base/sun.nio.ch.AsynchronousChannelGroupImpl$1.run(AsynchronousChannelGroupImpl.java:112) at
 org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191) at
 org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) at
 org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at
 java.base/java.lang.Thread.run(Thread.java:829)

 

Environment

• Liferay PaaS 7.3+

Resolution

• This happens because client is using special characters that aren’t supported by default.
• In order to change the parser config we need to modify the server.xml file and add the following:

relaxadoPathChars="[]|"
relaxadoQueryChars="[]|{}^\`"<>"

• For Liferay PaaS you can find this file in $REPO/liferay/configs/$ENVIRONMENT/tomcat/conf/server.xml and deploy it to make the change.

Additional Information

• Tomcat Configurations