Answers bug

when ever i try to go to answers page it gives me this error i just started seeing this error today this is what is says.

ERROR 500: solr Ex !

Exception

org.apache.solr.client.solrj.SolrServerException: Service Unavailable
Caused by:
Server side exception, status = 503: Service Unavailable
at org.apache.solr.client.solrj.impl.CommonsHttpSolrServer.request(CommonsHttpSolrServer.java:175)
at org.apache.solr.client.solrj.query.SolrQuery.process(SolrQuery.java:297)
at com.instructables.solr.SolrSearchServlet.doGet(SolrSearchServlet.java:486)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:115)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:92)
at com.caucho.server.dispatch.ServletFilterChain.doFilter(ServletFilterChain.java:106)
at com.caucho.filters.GzipFilter.doFilter(GzipFilter.java:208)
at com.instructables.filter.FilterWrapperFilter.doFilter(FilterWrapperFilter.java:47)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
at com.instructables.filter.HibernateSessionRequestFilter.doFilter(HibernateSessionRequestFilter.java:45)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
at com.instructables.filter.TemporaryProFilter.doFilter(TemporaryProFilter.java:77)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
at com.instructables.filter.SecurityFilter.doFilter(SecurityFilter.java:140)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
at com.instructables.filter.SetupFilter.doFilter(SetupFilter.java:68)
at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:70)
at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:173)
at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:229)
at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:274)
at com.caucho.server.port.TcpConnection.run(TcpConnection.java:514)
at com.caucho.util.ThreadPool.runTasks(ThreadPool.java:527)
at com.caucho.util.ThreadPool.run(ThreadPool.java:449)
at java.lang.Thread.run(Thread.java:595)