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>
      3 LOG Method=GET, PathInfo=null
      4 TIMER_START{handleSecurity}
   1292 TIMER_END{1287,handleSecurity} authenticator org.apache.sling.auth.core.impl.SlingAuthenticator@3e40e4e3 returns true
   1620 TIMER_START{ResourceResolution}
   2699 TIMER_END{1078,ResourceResolution} URI=/content/errors/404.html resolves to Resource=NonExistingResource, path=/content/errors/404.html
   2704 LOG Resource Path Info: SlingRequestPathInfo: path='/content/errors/404.html', selectorString='null', extension='html', suffix='null'
   2704 TIMER_START{ServletResolution}
   2708 TIMER_START{resolveServlet(/content/errors/404.html)}
   3329 LOG {0}: no servlet found
   3334 TIMER_END{625,resolveServlet(/content/errors/404.html)} Using servlet org.apache.sling.servlets.get.DefaultGetServlet
   3336 TIMER_END{631,ServletResolution} URI=/content/errors/404.html handled by Servlet=org.apache.sling.servlets.get.DefaultGetServlet
   3337 LOG Applying Requestfilters
   3343 LOG Calling filter: com.adobe.granite.resourceresolverhelper.impl.ResourceResolverHelperImpl
   3347 LOG Calling filter: org.apache.sling.security.impl.ContentDispositionFilter
   3349 LOG Calling filter: com.adobe.granite.csrf.impl.CSRFFilter
   3355 LOG Calling filter: org.apache.sling.i18n.impl.I18NFilter
   3358 LOG Calling filter: com.adobe.granite.httpcache.impl.InnerCacheFilter
   3362 LOG Calling filter: org.apache.sling.rewriter.impl.RewriterFilter
   3364 LOG Calling filter: com.day.cq.wcm.core.impl.WCMRequestFilter
   3366 LOG Calling filter: com.adobe.fd.core.security.internal.CurrentUserServiceImpl
   3706 LOG Calling filter: com.adobe.cq.wcm.core.components.internal.servlets.CoreFormHandlingServlet
   3709 LOG Calling filter: com.adobe.granite.optout.impl.OptOutFilter
   3713 LOG Calling filter: com.day.cq.wcm.foundation.forms.impl.FormsHandlingServlet
   3716 LOG Calling filter: com.adobe.cq.social.commons.cors.CORSAuthenticationFilter
   3718 LOG Calling filter: com.adobe.livecycle.dsc.clientsdk.internal.ResourceResolverHolderFilter
   3721 LOG Calling filter: org.apache.sling.engine.impl.debug.RequestProgressTrackerLogFilter
   3723 LOG Calling filter: com.adobe.livecycle.content.appcontext.impl.AppContextFilter
   3729 LOG Calling filter: com.adobe.cq.wcm.core.extensions.amp.internal.AmpModeForwardFilter
   3759 LOG Calling filter: wtc.core.filters.LoggingFilter
   3761 LOG Calling filter: org.panynj.jfk.core.filters.LoggingFilter
   3763 LOG Calling filter: com.day.cq.wcm.mobile.core.impl.redirect.RedirectFilter
   3765 LOG Calling filter: com.day.cq.wcm.core.impl.AuthoringUIModeServiceImpl
   3768 LOG Calling filter: com.adobe.granite.rest.assets.impl.AssetContentDispositionFilter
   3771 LOG Calling filter: com.adobe.granite.requests.logging.impl.RequestLoggerImpl
   3774 LOG Calling filter: com.adobe.granite.rest.impl.servlet.ApiResourceFilter
   3778 LOG Calling filter: com.day.cq.dam.core.impl.servlet.ActivityRecordHandler
   3784 LOG Calling filter: com.day.cq.dam.core.impl.assetlinkshare.AdhocAssetShareAuthHandler
   3787 LOG Calling filter: com.adobe.cq.social.ugcbase.security.impl.SaferSlingPostServlet
   3793 LOG Applying Componentfilters
   3794 LOG Calling filter: com.day.cq.personalization.impl.TargetComponentFilter
   3797 LOG Calling filter: com.day.cq.wcm.core.impl.page.PageLockFilter
   3799 LOG Calling filter: com.day.cq.wcm.core.impl.WCMComponentFilter
   3812 LOG Calling filter: com.day.cq.wcm.core.impl.WCMDebugFilter
   3818 TIMER_START{org.apache.sling.servlets.get.DefaultGetServlet#0}
   3898 TIMER_END{78,org.apache.sling.servlets.get.DefaultGetServlet#0}
   3938 LOG Filter timing: filter=com.day.cq.wcm.core.impl.WCMDebugFilter, inner=88, total=93, outer=5
   3944 LOG Filter timing: filter=com.day.cq.wcm.core.impl.WCMComponentFilter, inner=93, total=111, outer=18
   3950 LOG Filter timing: filter=com.day.cq.wcm.core.impl.page.PageLockFilter, inner=111, total=116, outer=5
   4032 LOG Filter timing: filter=com.adobe.cq.dtm.reactor.impl.servlets.ClientLibraryFilter, inner=0, total=162, outer=162
   4037 LOG Filter timing: filter=com.adobe.cq.dam.webdav.impl.io.DamWebdavRequestFilter, inner=162, total=163, outer=1
   4043 LOG Filter timing: filter=com.adobe.cq.social.ugcbase.security.impl.SaferSlingPostServlet, inner=163, total=167, outer=4
   4048 LOG Filter timing: filter=com.day.cq.dam.core.impl.assetlinkshare.AdhocAssetShareAuthHandler, inner=167, total=173, outer=6
   4054 LOG Filter timing: filter=com.adobe.cq.dtm.impl.servlets.DTMLibraryCompatibilityFilter, inner=173, total=174, outer=1
   4062 LOG Filter timing: filter=com.day.cq.dam.core.impl.servlet.DamContentDispositionFilter, inner=174, total=175, outer=1
   4067 LOG Filter timing: filter=com.day.cq.dam.core.impl.servlet.ActivityRecordHandler, inner=175, total=182, outer=7
   4073 LOG Filter timing: filter=com.adobe.granite.rest.impl.servlet.ApiResourceFilter, inner=182, total=188, outer=6
   4078 LOG Filter timing: filter=com.adobe.granite.requests.logging.impl.RequestLoggerImpl, inner=188, total=208, outer=20
   4083 LOG Filter timing: filter=com.adobe.granite.rest.assets.impl.AssetContentDispositionFilter, inner=208, total=214, outer=6
   4089 LOG Filter timing: filter=com.day.cq.wcm.core.impl.AuthoringUIModeServiceImpl, inner=214, total=219, outer=5
   4094 LOG Filter timing: filter=com.day.cq.wcm.mobile.core.impl.redirect.RedirectFilter, inner=219, total=223, outer=4
   4100 LOG Filter timing: filter=org.panynj.jfk.core.filters.LoggingFilter, inner=223, total=227, outer=4
   4105 LOG Filter timing: filter=wtc.core.filters.LoggingFilter, inner=227, total=232, outer=5
   4110 LOG Filter timing: filter=com.adobe.cq.wcm.core.extensions.amp.internal.AmpModeForwardFilter, inner=232, total=266, outer=34
   4116 LOG Filter timing: filter=com.adobe.livecycle.content.appcontext.impl.AppContextFilter, inner=266, total=272, outer=6
   4121 LOG Filter timing: filter=org.apache.sling.engine.impl.debug.RequestProgressTrackerLogFilter, inner=272, total=277, outer=5
   4126 LOG Filter timing: filter=com.adobe.livecycle.dsc.clientsdk.internal.ResourceResolverHolderFilter, inner=277, total=282, outer=5
   4131 LOG Filter timing: filter=com.adobe.cq.social.commons.cors.CORSAuthenticationFilter, inner=282, total=286, outer=4
   4136 LOG Filter timing: filter=com.day.cq.wcm.foundation.forms.impl.FormsHandlingServlet, inner=286, total=290, outer=4
   4142 LOG Filter timing: filter=com.adobe.granite.optout.impl.OptOutFilter, inner=290, total=296, outer=6
   4147 LOG Filter timing: filter=com.adobe.cq.wcm.core.components.internal.servlets.CoreFormHandlingServlet, inner=296, total=302, outer=6
   4152 LOG Filter timing: filter=com.adobe.fd.core.security.internal.CurrentUserServiceImpl, inner=302, total=643, outer=341
   4157 LOG Filter timing: filter=com.day.cq.wcm.core.impl.WCMRequestFilter, inner=643, total=648, outer=5
   4163 LOG Filter timing: filter=org.apache.sling.rewriter.impl.RewriterFilter, inner=648, total=652, outer=4
   4168 LOG Filter timing: filter=com.adobe.granite.httpcache.impl.InnerCacheFilter, inner=652, total=659, outer=7
   4173 LOG Filter timing: filter=org.apache.sling.i18n.impl.I18NFilter, inner=659, total=663, outer=4
   4178 LOG Filter timing: filter=com.adobe.granite.csrf.impl.CSRFFilter, inner=663, total=671, outer=8
   4183 LOG Filter timing: filter=org.apache.sling.security.impl.ContentDispositionFilter, inner=671, total=675, outer=4
   4189 LOG Filter timing: filter=org.apache.sling.distribution.servlet.DistributionAgentCreationFilter, inner=675, total=677, outer=2
   4315 LOG Applying Error filters
   4318 LOG Calling filter: org.apache.sling.i18n.impl.I18NFilter
   4320 LOG Calling filter: org.apache.sling.rewriter.impl.RewriterFilter
   4323 TIMER_START{handleError:status=404}
   4612 TIMER_END{288,handleError:status=404} Using handler Sling (Ad Hoc) Default Error Handler Servlet
   5268 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={}))}
   5408 TIMER_END{5407,Request Processing} Dumping SlingRequestProgressTracker Entries

Apache Sling