error :

Resource at '/content/ready/partners/ae/aem/sites.html' not found: No resource found

Cannot serve request to /aem/sites.html in /libs/sling/servlet/errorhandler/404.jsp

Request Progress:

      0 TIMER_START{Request Processing}
      1 COMMENT timer_end format is {<elapsed microseconds>,<timer name>} <optional message>
      5 LOG Method=GET, PathInfo=null
      5 TIMER_START{handleSecurity}
   1268 TIMER_END{1262,handleSecurity} authenticator org.apache.sling.auth.core.impl.SlingAuthenticator@786eba1b returns true
   1567 TIMER_START{ResourceResolution}
   1807 TIMER_END{239,ResourceResolution} URI=/aem/sites.html resolves to Resource=NonExistingResource, path=/content/ready/partners/ae/aem/sites.html
   1812 LOG Resource Path Info: SlingRequestPathInfo: path='/content/ready/partners/ae/aem/sites.html', selectorString='null', extension='html', suffix='null'
   1812 TIMER_START{ServletResolution}
   1814 TIMER_START{resolveServlet(/content/ready/partners/ae/aem/sites.html)}
   2673 LOG {0}: no servlet found
   2677 TIMER_END{862,resolveServlet(/content/ready/partners/ae/aem/sites.html)} Using servlet org.apache.sling.servlets.get.DefaultGetServlet
   2680 TIMER_END{867,ServletResolution} URI=/aem/sites.html handled by Servlet=org.apache.sling.servlets.get.DefaultGetServlet
   2682 LOG Applying Requestfilters
   2688 LOG Calling filter: com.adobe.granite.resourceresolverhelper.impl.ResourceResolverHelperImpl
   2694 LOG Calling filter: org.apache.sling.security.impl.ContentDispositionFilter
   2697 LOG Calling filter: com.adobe.granite.csrf.impl.CSRFFilter
   2703 LOG Calling filter: org.apache.sling.i18n.impl.I18NFilter
   2706 LOG Calling filter: com.adobe.granite.httpcache.impl.InnerCacheFilter
   2711 LOG Calling filter: org.apache.sling.rewriter.impl.RewriterFilter
   2714 LOG Calling filter: com.adobe.cq.history.impl.HistoryRequestFilter
   2907 LOG Calling filter: com.day.cq.wcm.core.impl.WCMRequestFilter
   2914 LOG Calling filter: com.adobe.acs.commons.redirects.filter.RedirectFilter
   2926 LOG Calling filter: com.adobe.cq.wcm.core.components.internal.servlets.CoreFormHandlingServlet

@annkitaaggarwal Seems like the instance is corrupted/ instance was terminated abnormally, You would probably need to create a fresh crx-quickstart folder.

you can use also make use of backup and restore, proabably will be useful in such situations-

https://experienceleague.adobe.com/docs/experience-manager-64/administering/operations/backup-and-restore.html?lang=en

Hope this helps.