Applications based on the Jersey implementation to create API ,sometimes failed to start due to below error. The ResourceConfig instance does not contain any root resource classes. Main cause of this issue is configuration problem in web.xml

In any jersey based application we need to add below Servlet settings in web.xml


<servlet>
    <servlet-name>jersey-serlvet</servlet-name>
    <servlet-class>com.sun.jersey.spi.container.servlet.ServletContainer</servlet-class>
    <init-param>
      <param-name>com.sun.jersey.config.property.packages</param-name>
      <param-value>com.rest</param-value>
    </init-param>
    <init-param>
      <param-name>com.sun.jersey.api.json.POJOMappingFeature</param-name>
      <param-value>true</param-value>
    </init-param>
    <load-on-startup>2</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>jersey-serlvet</servlet-name>
    <url-pattern>/rest/*</url-pattern>
  </servlet-mapping>

Here important parameter to see is below

<init-param>
      <param-name>com.sun.jersey.config.property.packages</param-name>
      <param-value>com.rest</param-value>
</init-param>




Param value your passing should be the package where jersey implementation are available. 


if no jersey implementation found then container will through this error.