Resource at '/content/errors/404.html' not found: No resource found (404)

The requested URL /content/errors/404.html resulted in an error in Sling (Ad Hoc) Default Error Handler Servlet.

Request Progress:

      0 TIMER_START{Request Processing}
      0 COMMENT timer_end format is {<elapsed microseconds>,<timer name>} <optional message>
      2 LOG Method=GET, PathInfo=null
      3 TIMER_START{handleSecurity}
   1201 TIMER_END{1197,handleSecurity} authenticator org.apache.sling.auth.core.impl.SlingAuthenticator@3e40e4e3 returns true
   1482 TIMER_START{ResourceResolution}
   2569 TIMER_END{1086,ResourceResolution} URI=/content/errors/404.html resolves to Resource=NonExistingResource, path=/content/errors/404.html
   2573 LOG Resource Path Info: SlingRequestPathInfo: path='/content/errors/404.html', selectorString='null', extension='html', suffix='null'
   2574 TIMER_START{ServletResolution}
   2577 TIMER_START{resolveServlet(/content/errors/404.html)}
   3201 LOG {0}: no servlet found
   3205 TIMER_END{627,resolveServlet(/content/errors/404.html)} Using servlet org.apache.sling.servlets.get.DefaultGetServlet
   3208 TIMER_END{633,ServletResolution} URI=/content/errors/404.html handled by Servlet=org.apache.sling.servlets.get.DefaultGetServlet
   3208 LOG Applying Requestfilters
   3212 LOG Calling filter: com.adobe.granite.resourceresolverhelper.impl.ResourceResolverHelperImpl
   3216 LOG Calling filter: org.apache.sling.security.impl.ContentDispositionFilter
   3218 LOG Calling filter: com.adobe.granite.csrf.impl.CSRFFilter
   3223 LOG Calling filter: org.apache.sling.i18n.impl.I18NFilter
   3225 LOG Calling filter: com.adobe.granite.httpcache.impl.InnerCacheFilter
   3228 LOG Calling filter: org.apache.sling.rewriter.impl.RewriterFilter
   3230 LOG Calling filter: com.day.cq.wcm.core.impl.WCMRequestFilter
   3233 LOG Calling filter: com.adobe.fd.core.security.internal.CurrentUserServiceImpl
   3483 LOG Calling filter: com.adobe.cq.wcm.core.components.internal.servlets.CoreFormHandlingServlet
   3485 LOG Calling filter: com.adobe.granite.optout.impl.OptOutFilter
   3488 LOG Calling filter: com.day.cq.wcm.foundation.forms.impl.FormsHandlingServlet
   3490 LOG Calling filter: com.adobe.cq.social.commons.cors.CORSAuthenticationFilter
   3492 LOG Calling filter: com.adobe.livecycle.dsc.clientsdk.internal.ResourceResolverHolderFilter
   3494 LOG Calling filter: org.apache.sling.engine.impl.debug.RequestProgressTrackerLogFilter
   3496 LOG Calling filter: com.adobe.livecycle.content.appcontext.impl.AppContextFilter
   3501 LOG Calling filter: com.adobe.cq.wcm.core.extensions.amp.internal.AmpModeForwardFilter
   3551 LOG Calling filter: wtc.core.filters.LoggingFilter
   3552 LOG Calling filter: org.panynj.jfk.core.filters.LoggingFilter
   3557 LOG Calling filter: com.day.cq.wcm.mobile.core.impl.redirect.RedirectFilter
   3559 LOG Calling filter: com.day.cq.wcm.core.impl.AuthoringUIModeServiceImpl
   3561 LOG Calling filter: com.adobe.granite.rest.assets.impl.AssetContentDispositionFilter
   3564 LOG Calling filter: com.adobe.granite.requests.logging.impl.RequestLoggerImpl
   3567 LOG Calling filter: com.adobe.granite.rest.impl.servlet.ApiResourceFilter
   3569 LOG Calling filter: com.day.cq.dam.core.impl.servlet.ActivityRecordHandler
   3575 LOG Calling filter: com.day.cq.dam.core.impl.assetlinkshare.AdhocAssetShareAuthHandler
   3577 LOG Calling filter: com.adobe.cq.social.ugcbase.security.impl.SaferSlingPostServlet
   3582 LOG Applying Componentfilters
   3583 LOG Calling filter: com.day.cq.personalization.impl.TargetComponentFilter
   3586 LOG Calling filter: com.day.cq.wcm.core.impl.page.PageLockFilter
   3588 LOG Calling filter: com.day.cq.wcm.core.impl.WCMComponentFilter
   3599 LOG Calling filter: com.day.cq.wcm.core.impl.WCMDebugFilter
   3606 TIMER_START{org.apache.sling.servlets.get.DefaultGetServlet#0}
   3671 TIMER_END{65,org.apache.sling.servlets.get.DefaultGetServlet#0}
   3709 LOG Filter timing: filter=com.day.cq.wcm.core.impl.WCMDebugFilter, inner=74, total=79, outer=5
   3715 LOG Filter timing: filter=com.day.cq.wcm.core.impl.WCMComponentFilter, inner=79, total=96, outer=17
   3720 LOG Filter timing: filter=com.day.cq.wcm.core.impl.page.PageLockFilter, inner=96, total=101, outer=5
   3799 LOG Filter timing: filter=com.adobe.cq.dtm.reactor.impl.servlets.ClientLibraryFilter, inner=0, total=141, outer=141
   3804 LOG Filter timing: filter=com.adobe.cq.dam.webdav.impl.io.DamWebdavRequestFilter, inner=141, total=142, outer=1
   3809 LOG Filter timing: filter=com.adobe.cq.social.ugcbase.security.impl.SaferSlingPostServlet, inner=142, total=147, outer=5
   3814 LOG Filter timing: filter=com.day.cq.dam.core.impl.assetlinkshare.AdhocAssetShareAuthHandler, inner=147, total=151, outer=4
   3819 LOG Filter timing: filter=com.adobe.cq.dtm.impl.servlets.DTMLibraryCompatibilityFilter, inner=151, total=152, outer=1
   3825 LOG Filter timing: filter=com.day.cq.dam.core.impl.servlet.DamContentDispositionFilter, inner=152, total=153, outer=1
   3829 LOG Filter timing: filter=com.day.cq.dam.core.impl.servlet.ActivityRecordHandler, inner=153, total=160, outer=7
   3852 LOG Filter timing: filter=com.adobe.granite.rest.impl.servlet.ApiResourceFilter, inner=160, total=165, outer=5
   3857 LOG Filter timing: filter=com.adobe.granite.requests.logging.impl.RequestLoggerImpl, inner=165, total=183, outer=18
   3862 LOG Filter timing: filter=com.adobe.granite.rest.assets.impl.AssetContentDispositionFilter, inner=183, total=189, outer=6
   3868 LOG Filter timing: filter=com.day.cq.wcm.core.impl.AuthoringUIModeServiceImpl, inner=189, total=194, outer=5
   3873 LOG Filter timing: filter=com.day.cq.wcm.mobile.core.impl.redirect.RedirectFilter, inner=194, total=200, outer=6
   3878 LOG Filter timing: filter=org.panynj.jfk.core.filters.LoggingFilter, inner=200, total=204, outer=4
   3883 LOG Filter timing: filter=wtc.core.filters.LoggingFilter, inner=204, total=207, outer=3
   3888 LOG Filter timing: filter=com.adobe.cq.wcm.core.extensions.amp.internal.AmpModeForwardFilter, inner=207, total=262, outer=55
   3894 LOG Filter timing: filter=com.adobe.livecycle.content.appcontext.impl.AppContextFilter, inner=262, total=267, outer=5
   3899 LOG Filter timing: filter=org.apache.sling.engine.impl.debug.RequestProgressTrackerLogFilter, inner=267, total=271, outer=4
   3904 LOG Filter timing: filter=com.adobe.livecycle.dsc.clientsdk.internal.ResourceResolverHolderFilter, inner=271, total=275, outer=4
   3909 LOG Filter timing: filter=com.adobe.cq.social.commons.cors.CORSAuthenticationFilter, inner=275, total=279, outer=4
   3914 LOG Filter timing: filter=com.day.cq.wcm.foundation.forms.impl.FormsHandlingServlet, inner=279, total=283, outer=4
   3925 LOG Filter timing: filter=com.adobe.granite.optout.impl.OptOutFilter, inner=283, total=288, outer=5
   3930 LOG Filter timing: filter=com.adobe.cq.wcm.core.components.internal.servlets.CoreFormHandlingServlet, inner=288, total=293, outer=5
   3936 LOG Filter timing: filter=com.adobe.fd.core.security.internal.CurrentUserServiceImpl, inner=293, total=544, outer=251
   3941 LOG Filter timing: filter=com.day.cq.wcm.core.impl.WCMRequestFilter, inner=544, total=548, outer=4
   3946 LOG Filter timing: filter=org.apache.sling.rewriter.impl.RewriterFilter, inner=548, total=552, outer=4
   3951 LOG Filter timing: filter=com.adobe.granite.httpcache.impl.InnerCacheFilter, inner=552, total=559, outer=7
   3956 LOG Filter timing: filter=org.apache.sling.i18n.impl.I18NFilter, inner=559, total=563, outer=4
   3962 LOG Filter timing: filter=com.adobe.granite.csrf.impl.CSRFFilter, inner=563, total=570, outer=7
   3967 LOG Filter timing: filter=org.apache.sling.security.impl.ContentDispositionFilter, inner=570, total=574, outer=4
   3973 LOG Filter timing: filter=org.apache.sling.distribution.servlet.DistributionAgentCreationFilter, inner=574, total=575, outer=1
   4086 LOG Applying Error filters
   4089 LOG Calling filter: org.apache.sling.i18n.impl.I18NFilter
   4091 LOG Calling filter: org.apache.sling.rewriter.impl.RewriterFilter
   4094 TIMER_START{handleError:status=404}
   4347 TIMER_END{252,handleError:status=404} Using handler Sling (Ad Hoc) Default Error Handler Servlet
   4987 LOG Found processor for post processing ProcessorConfiguration: {contentTypes=[text/html], order=1, active=true, valid=true, processErrorResponse=true, pipeline=(generator=Config(type=htmlparser, config={}), transformers=(Config(type=linkchecker, config={}), Config(type=mobile, config=JcrPropertyMap [node=Node[NodeDelegate{tree=/apps/portauthority/config/rewriter/default/transformer-mobile: { jcr:primaryType = nt:unstructured, component-optional = true}}], values={jcr:primaryType=nt:unstructured, component-optional=true}]), Config(type=mobiledebug, config=JcrPropertyMap [node=Node[NodeDelegate{tree=/apps/portauthority/config/rewriter/default/transformer-mobiledebug: { jcr:primaryType = nt:unstructured, component-optional = true}}], values={jcr:primaryType=nt:unstructured, component-optional=true}]), Config(type=contentsync, config=JcrPropertyMap [node=Node[NodeDelegate{tree=/apps/portauthority/config/rewriter/default/transformer-contentsync: { jcr:primaryType = nt:unstructured, component-optional = true}}], values={jcr:primaryType=nt:unstructured, component-optional=true}]), Config(type=versioned-clientlibs, config={}), serializer=Config(type=htmlwriter, config={}))}
   5108 TIMER_END{5107,Request Processing} Dumping SlingRequestProgressTracker Entries

Apache Sling