Republish causes warning: Servlet Faces Servlet is currently unavailable

Question

I'm using Mojarra 2.2 on Tomcat 8 and Eclipse 4.4.1 (Build id: 20140925-1800) without any additional plugins and no Maven.

Everything works fine, but in last few days I have the following problem:

I start Tomcat, can navigate and submit data, etc, everything works correct. Now if I change my Java code, then Tomcat republishes as usual, but if I try to refresh the page in browser via F5, then I get the following error:

HTTP Status 503 - Servlet Faces Servlet is currently unavailable

In Eclipse console the following appears:

Apr 27, 2015 5:18:27 PM org.apache.catalina.core.ApplicationDispatcher invoke
WARNUNG: Servlet Faces Servlet is currently unavailable

Now I have to restart Tomcat after every little change in Java source code in order to solve it.

I don't know since when I have this issue, but I am sure I haven't it before. I changed many things in the project, but I cannot figure out the cause of this problem.

Here's a snippet of my web.xml:

    <?xml version="1.0" encoding="UTF-8"?>
    <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
    .....
    .....
    <servlet>
            <servlet-name>Faces Servlet</servlet-name>
            <servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
            <load-on-startup>1</load-on-startup>
        </servlet>
        <servlet-mapping>
            <servlet-name>Faces Servlet</servlet-name>
            <url-pattern>/ps/*</url-pattern>
        </servlet-mapping>

        <context-param>
            <description>State saving method: 'client' or 'server' (=default). See JSF Specification 2.5.2</description>
            <param-name>javax.faces.STATE_SAVING_METHOD</param-name>
            <param-value>client</param-value>
        </context-param>
        <context-param>
            <param-name>javax.servlet.jsp.jstl.fmt.localizationContext</param-name>
            <param-value>resources.application</param-value>
        </context-param>
        <context-param>
            <param-name>javax.faces.DEFAULT_SUFFIX</param-name>
            <param-value>.xhtml</param-value>
        </context-param>
        <context-param>
            <param-name>facelets.DEVELOPMENT</param-name>
            <param-value>true</param-value>
        </context-param>
        <context-param>
            <param-name>javax.faces.FACELETS_REFRESH_PERIOD</param-name>
            <param-value>0</param-value>
        </context-param>

        <context-param>
            <param-name>javax.faces.PROJECT_STAGE</param-name>
            <param-value>Development</param-value>
        </context-param>
        <context-param>
            <param-name>javax.faces.CONFIG_FILES</param-name>
            <param-value>/WEB-INF/faces-config.xml,/WEB-INF/navigations.xml</param-value>
        </context-param>
    ....
    <listener>
            <listener-class>com.sun.faces.config.ConfigureListener</listener-class>
        </listener>

    ....
    <security-constraint>
            <display-name>Restrict XHTML Documents</display-name>
            <web-resource-collection>
                <web-resource-name>XHTML</web-resource-name>
                <url-pattern>*.xhtml</url-pattern>
            </web-resource-collection>
        </security-constraint>
    <session-config>
            <session-timeout>60</session-timeout>
            <tracking-mode>COOKIE</tracking-mode>
        </session-config>

        <error-page>
            <exception-type>javax.faces.application.ViewExpiredException</exception-type>
            <location>/index.jsp</location>
        </error-page>
        <locale-encoding-mapping-list>
            <locale-encoding-mapping>
                <locale>de</locale>
                <encoding>UTF-8</encoding>
            </locale-encoding-mapping>
        </locale-encoding-mapping-list>
</web-app>

How is this caused and how can I solve it?