Symptoms

The encoding test shows that the string passed for database round-trip is wrong and the string is modified after submission.

Cause

1. Confluence is configured to use Kerberos Authenticator in <installation-directory>/Confluence/WEB-INF/classes/seraph-config.xml
2. Confluence is configured to use a Custom Authenticator in <installation-directory>/Confluence/WEB-INF/classes/seraph-config.xml. A filter mapping has been added to web.xml above the 'encoding' filters.  

Resolution #1

• Add the following mapping filter in  <installation dir>/confluence/WEB-INF/web.xml:

  <filter-mapping>
  <filter-name>login</filter-name>
  <url-pattern>/*</url-pattern>
  </filter-mapping>

• More details about this configuration explained here

 After editing the  web.xml  file, you will need to restart Confluence for your change to take effect.

Resolution #2

• Ensure that no filters exist in <installation dir>/confluence/WEB-INF/web.xml above the 'encoding' filters (as shown below):

    <!-- THIS MUST REMAIN AS THE TOP FILTER SO THAT THE ENCODING CAN BE SET BEFORE ANYTHING ELSE TOUCHES IT (well, except the header sanitiser)-->
      <filter-mapping>
          <filter-name>encoding</filter-name>
          <url-pattern>*.vm</url-pattern>
      </filter-mapping>
      <filter-mapping>
          <filter-name>encoding</filter-name>
          <url-pattern>/display/*</url-pattern>
      </filter-mapping>
      <filter-mapping>
          <filter-name>encoding</filter-name>
          <url-pattern>*.action</url-pattern>
      </filter-mapping>
      <filter-mapping>
          <filter-name>encoding</filter-name>
          <url-pattern>/download/*</url-pattern>
      </filter-mapping>
      <filter-mapping>
          <filter-name>encoding</filter-name>
          <url-pattern>/plugins/servlet/*</url-pattern>
      </filter-mapping>
      <filter-mapping>
          <filter-name>encoding</filter-name>
          <url-pattern>/label/*</url-pattern>
      </filter-mapping>
      <filter-mapping>
          <filter-name>encoding</filter-name>
          <url-pattern>/s/*</url-pattern>
      </filter-mapping>
  <<--New filters should be added here

 After editing the  web.xml  file, you will need to restart Confluence for your change to take effect.