Tomcat Invalid character found in the request target

While running an application in the tomcat server, sometimes we might get the following error.

org.apache.coyote.http11.Http11Processor.service Error parsing HTTP request header
 Note: further occurrences of HTTP request parsing errors will be logged at DEBUG level.
	java.lang.IllegalArgumentException: Invalid character found in the request target [/index.php?s=/Index/\think\app/invokefunction&function=call_user_func_array&vars[0]=md5&vars[1][]=HelloThinkPHP21 ]. The valid characters are defined in RFC 7230 and RFC 3986
		at org.apache.coyote.http11.Http11InputBuffer.parseRequestLine(Http11InputBuffer.java:509)
		at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:511)
		at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
		at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:831)
		at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1673)
		at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
		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.lang.Thread.run(Thread.java:748)

First, make sure that the domain pointed to the server is working fine or not expired.

From tomcat, it is suggested that

The HTTP/1.1 specification requires that certain characters are %nn encoded when used in URI query strings. Unfortunately, many user agents including all the major browsers are not compliant with this specification and use these characters in unencoded form. To prevent Tomcat rejecting such requests, this attribute may be used to specify the additional characters to allow. If not specified, no additional characters will be allowed. The value may be any combination of the following characters: " < > [ \ ] ^ ` { | } . Any other characters present in the value will be ignored.

Tomcat increased its security and no longer allows raw square brackets or the above characters in the query string.

In order to resolve this issue use relaxedQueryChars attributes inside the server.xml file of tomcat server. Make sure to back up the server.xml file before we change it.

Open the server.xml file using vim or vi and type Shift + i

sudo vim /path_to_tomcat/conf/server.xml

Press Esc and hit :wq! and save the changes

Restart the tomcat server.

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How to resolve the encoding issue while building Java Application

In this tutorial, we are going to understand the different scenarios where we might get encoding issues while building the Java application as a war or jar file and deploy it to the server. 

The main encoding issue here is, for some languages like Hebrew, Chinese, Arabic, etc there might get the chance of appearing as question marks instead of actual specific text. This issue might be due to different cases.

1. Sometimes the serverside rendering language like jsp, gsp pages might cause the issue we can use the following tag in those pages.

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>

2. We might get the issue due to database data where we don't set the configugre the utf-8 encoding. To resolve the issue we can set the jdbc connection url as follows:

jdbc:mysql://hostname/database_naeme?useUnicode=yes&&characterEncoding=UTF-8

3. If our application contains some other language that requires saving operation in the database. Better to create the database using encoding using the following command for the MySQL database.

CREATE DATABASE database_name DEFAULT CHARACTER SET "utf8" COLLATE "utf8_general_ci";

Make sure to change the actual database instead of [database_name].

4. If we are using hibernate then better to configure the settings as

hibernate.connection.charSet=UTF-8
hibernate.connection.characterEncoding=UTF-8
hibbernate.connection.useUnicode=true

5. If we are using build tools like Jenkins for deployment we need to configure the encoding In Jenkins: we can create a global variable and set encoding config as below:

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