As originally described in: https://support.atlassian.com/browse/CSP-2337

In Confluence search toppage, Japanese double byte query cannot be sent correctly. It works correctly with the search box in global header. The search box in the search toppage might be sending a query in non UTF-8 encoding.

Although a temporary fix was described (as below) I believe we still need to improve something here.

TEMPORARY FIX:

You need to set the URIEncoding attribute of the Connector tag in server.xml to UTF-8:

e.g. <Connector className="org.apache.coyote.tomcat4.CoyoteConnector" port="8080" minProcessors="5" maxProcessors="75"
enableLookups="true" redirectPort="8443" acceptCount="10" debug="0" connectionTimeout="20000" useURIValidationHack="false"
URIEncoding="UTF-8"/>