Webdav door errors : Detector [proxy] failed to detect upgrade target

[ageorget]

Hi,

Recently, we started to see errors like this in the Webdav doors logs for our Rubin dCache instance (11.2.4).

Sep 15 17:06:11 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]: 15 Sep 2026 17:06:11 (webdav-http-ccdcacli492) [] Detector [proxy] error for SocketChannelEndPoint@499616b2{l=/[20
01:660:5009:320:134:158:227:25]:4080,r=/[2001:660:5009:17:134:158:170:19]:33910,OPEN,fill=-,flush=-,to=0/300000}{io=0/0,kio=0,kro=1}->DetectorConnection@6210ed60
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]: [Fatal Error] :1:1: Content is not allowed in prolog.
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]: 15 Sep 2026 17:06:36 (webdav-http-ccdcacli492) [door:webdav-http-ccdcacli492@webdavhttp-ccdcacli492Domain:AAZbhuWl
MlI] exception parsing request body
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]: org.xml.sax.SAXParseException: Content is not allowed in prolog.
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at java.xml/com.sun.org.apache.xerces.internal.parsers.AbstractSAXParser.parse(AbstractSAXParser.java:1251
)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at io.milton.http.webdav.DefaultPropFindRequestFieldParser.getRequestedFields(DefaultPropFindRequestFieldP
arser.java:70)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at io.milton.http.webdav.MsPropFindRequestFieldParser.getRequestedFields(MsPropFindRequestFieldParser.java
:50)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at io.milton.http.webdav.PropFindHandler.processExistingResource(PropFindHandler.java:124)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at io.milton.http.ResourceHandlerHelper.processResource(ResourceHandlerHelper.java:196)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at io.milton.http.webdav.PropFindHandler.processResource(PropFindHandler.java:112)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at io.milton.http.ResourceHandlerHelper.process(ResourceHandlerHelper.java:127)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.dcache.webdav.DcacheResourceHandlerHelper.process(DcacheResourceHandlerHelper.java:42)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at io.milton.http.webdav.PropFindHandler.process(PropFindHandler.java:106)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.dcache.webdav.DcacheStandardFilter.process(DcacheStandardFilter.java:50)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at io.milton.http.FilterChain.process(FilterChain.java:46)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.dcache.webdav.transfer.CopyFilter.process(CopyFilter.java:305)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at io.milton.http.FilterChain.process(FilterChain.java:46)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at io.milton.http.HttpManager.process(HttpManager.java:158)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.dcache.webdav.MiltonHandler.handle(MiltonHandler.java:77)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.eclipse.jetty.server.handler.HandlerList.handle(HandlerList.java:59)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.dcache.http.AuthenticationHandler.access$001(AuthenticationHandler.java:55)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.dcache.http.AuthenticationHandler.lambda$handle$0(AuthenticationHandler.java:157)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at java.base/java.security.AccessController.doPrivileged(AccessController.java:400)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at java.base/javax.security.auth.Subject.doAs(Subject.java:453)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.dcache.http.AuthenticationHandler.handle(AuthenticationHandler.java:154)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.eclipse.jetty.server.handler.HandlerList.handle(HandlerList.java:59)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.dcache.http.AbstractLoggingHandler.handle(AbstractLoggingHandler.java:124)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.dcache.util.jetty.RateLimitedHandlerList.handle(RateLimitedHandlerList.java:246)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.eclipse.jetty.rewrite.handler.RewriteHandler.handle(RewriteHandler.java:322)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.eclipse.jetty.server.Server.handle(Server.java:516)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.eclipse.jetty.server.HttpChannel.lambda$handle$1(HttpChannel.java:487)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:732)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:479)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:277)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.eclipse.jetty.server.HttpConnection.run(HttpConnection.java:531)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:883)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1034)
Sep 15 17:06:36 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]:         at java.base/java.lang.Thread.run(Thread.java:1583)
Sep 15 17:18:14 ccdcacli492 dcache@webdavhttp-ccdcacli492Domain[1391838]: 15 Sep 2026 17:18:14 (webdav-http-ccdcacli492) [] Detector [proxy] failed to detect upgrade target on [ProxyV1ConnectionFactory@24fa41cb[proxy], ProxyV2ConnectionFactory@7fd037a7[proxy]] for SocketChannelEndPoint@64ae66d5{l=/[2001:660:5009:320:134:158:227:25]:4080,r=/[2001:660:5009:17:134:158:170:19]:58976,OPEN,fill=-,flush=-,to=0/300000}{io=0/0,kio=0,kro=1}->DetectorConnection@29c2256e

Can you help us to understand where they come from?