cvc-complex-type.2.4.c: The matching wildcard is strict, but no declaration can be found for element 'aop:scoped-proxy'

I have a Spring MvC project using JPA and Oracle as DB, I have this bean declaration in my servlet.xml file, but when I run a test

<beans xmlns="http://www.springframework.org/schema/beans"

    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:jpa="http://www.springframework.org/schema/data/jpa"
    xmlns:tx="http://www.springframework.org/schema/tx"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="http://www.springframework.org/schema/data/jpa
    http://www.springframework.org/schema/data/jpa/spring-jpa.xsd
    http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context 
    http://www.springframework.org/schema/context/spring-context.xsd
    http://www.springframework.org/schema/tx
    http://www.springframework.org/schema/aop
    http://www.springframework.org/schema/aop/spring-aop.xsd
    http://www.springframework.org/schema/tx/spring-tx.xsd">

<bean id="bbtra" 
        class="com.bonanza.commons.services.TranslationDB"
        autowire-candidate="true">
    <property name="dataSource" ref="dataSource" />
    <aop:scoped-proxy/>
</bean>

I got this error:

cvc-complex-type.2.4.c: The matching wildcard is strict, but no declaration can be found for element 'aop:scoped-proxy'.

Most probably schema location of the aop namespace is not specified:

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/aop https://www.springframework.org/schema/aop/spring-aop.xsd">

    <!-- bean definitions here -->

</beans>

Usually the *.xsd files are referenced by https:// instead of http://, but that is not the problem, I am just mentioning it. The minimal change to your XML file fixing the problem is moving up spring-tx.xsd to be right behind tx. Then also the highlighting in your XML editor changes, i.e. in IntelliJ IDEA you will see the AOP stuff go from grey to green. What I mean is:

<beans
  xmlns="http://www.springframework.org/schema/beans"
  xmlns:context="http://www.springframework.org/schema/context"
  xmlns:jpa="http://www.springframework.org/schema/data/jpa"
  xmlns:tx="http://www.springframework.org/schema/tx"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns:aop="http://www.springframework.org/schema/aop"
  xsi:schemaLocation="
    http://www.springframework.org/schema/data/jpa
    http://www.springframework.org/schema/data/jpa/spring-jpa.xsd
    http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd
    http://www.springframework.org/schema/tx
    http://www.springframework.org/schema/tx/spring-tx.xsd
    http://www.springframework.org/schema/aop
    http://www.springframework.org/schema/aop/spring-aop.xsd
  "
>

  <bean id="bbtra"
    class="com.bonanza.commons.services.TranslationDB"
    autowire-candidate="true">
    <property name="dataSource" ref="dataSource" />
    <aop:scoped-proxy/>
  </bean>

</beans>

Now all schema locations schema/foo and schema/foo/spring-foo.xsd form pairs.