Cannot change HTTP accept header – use a different locale resolution strategy

Problem

In Spring MVC application, while changing the locale with “org.springframework.web.servlet.i18n.LocaleChangeInterceptor“, it hits the following error

java.lang.UnsupportedOperationException: 
     Cannot change HTTP accept header - use a different locale resolution strategy
     ...AcceptHeaderLocaleResolver.setLocale(AcceptHeaderLocaleResolver.java:45)

Solution

In Spring MVC application, if you do not configure the Spring’s LocaleResolver, it will use the default AcceptHeaderLocaleResolver, which does not allow to change the locale. To solve it, try declare a SessionLocaleResolver bean in the Spring bean configuration file, it should be suits in most cases.

<beans ...

	<bean id="localeResolver"
		class="org.springframework.web.servlet.i18n.SessionLocaleResolver">
		<property name="defaultLocale" value="en" />
	</bean>

	<bean id="localeChangeInterceptor"
		class="org.springframework.web.servlet.i18n.LocaleChangeInterceptor">
		<property name="paramName" value="language" />
	</bean>
	
	<bean class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping" >
		<property name="interceptors">
			<list>
				<ref bean="localeChangeInterceptor" />
			</list>
		</property>
	</bean>
	
</beans>

Reference

1. LocaleResolver documentation