Export as HTML not working on jetty installations

2022-02-01 10:43:01,469 [qtp1012570586-290 - http://localhost:8080/xwiki/bin/export/Sandbox/TestPage3?format=html] WARN  c.x.x.w.XWikiAction            - Uncaught exception: Error number 11015 in 11: Exception while exporting 2022-02-01 10:43:01,469 [qtp1012570586-290 - http://localhost:8080/xwiki/bin/export/Sandbox/TestPage3?format=html] WARN  c.x.x.w.XWikiAction            - Uncaught exception: Error number 11015 in 11: Exception while exporting com.xpn.xwiki.XWikiException: Error number 11015 in 11: Exception while exporting at com.xpn.xwiki.web.ExportAction.render(ExportAction.java:101) at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:590) at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:289) at com.xpn.xwiki.web.LegacyActionServlet.service(LegacyActionServlet.java:115) at javax.servlet.http.HttpServlet.service(HttpServlet.java:790) at org.eclipse.jetty.servlet.ServletHolder$NotAsync.service(ServletHolder.java:1459) at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:799) at org.eclipse.jetty.servlet.ServletHandler$ChainEnd.doFilter(ServletHandler.java:1631) at com.xpn.xwiki.web.ActionFilter.doFilter(ActionFilter.java:122) at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193) at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601) at org.xwiki.wysiwyg.filter.ConversionFilter.doFilter(ConversionFilter.java:61) at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193) at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601) at org.eclipse.jetty.websocket.server.WebSocketUpgradeFilter.doFilter(WebSocketUpgradeFilter.java:228) at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193) at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601) at org.xwiki.container.servlet.filters.internal.SetHTTPHeaderFilter.doFilter(SetHTTPHeaderFilter.java:63) at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193) at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601) at org.xwiki.container.servlet.filters.internal.SavedRequestRestorerFilter.doFilter(SavedRequestRestorerFilter.java:208) at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193) at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601) at org.xwiki.container.servlet.filters.internal.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:111) at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193) at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601) at org.xwiki.resource.servlet.RoutingFilter.doFilter(RoutingFilter.java:132) at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:201) at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601) at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:548) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143) at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:600) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127) at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:235) at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1624) at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233) at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1434) at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188) at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:501) at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1594) at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:186) at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1349) at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141) at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:191) at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:146) at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127) at org.eclipse.jetty.server.Server.handle(Server.java:516) at org.eclipse.jetty.server.HttpChannel.lambda$handle$1(HttpChannel.java:400) at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:645) at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:392) at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:277) at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:311) at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:105) at org.eclipse.jetty.io.ChannelEndPoint$1.run(ChannelEndPoint.java:104) at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:338) at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:315) at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:173) at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:131) at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:409) at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:883) at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1034) at java.base/java.lang.Thread.run(Unknown Source)Caused by: java.lang.NullPointerException: null at java.base/java.io.File.<init>(Unknown Source) at com.xpn.xwiki.export.html.HtmlPackager.addSkinToZip(HtmlPackager.java:472) at com.xpn.xwiki.export.html.HtmlPackager.export(HtmlPackager.java:388) at com.xpn.xwiki.web.ExportAction.exportHTML(ExportAction.java:149) at com.xpn.xwiki.web.ExportAction.render(ExportAction.java:96) ... 61 common frames omitted 

context.getWiki().getEngineContext().getRealPath("/skins/" + skinName)

urlf.getFilesystemExportContext().getNeededSkins() 

[[skin, flamingo]]

addSkinToZip(skinName, zos, urlf.getFilesystemExportContext().getExportedSkinFiles(), context);