Document Upload causes java.io.IOException:

Hello,

we have a new Installation of XWIKI 13.01. (Docker). Now, if we try to upload a Document we get a “Network error” and I found this message.

2021-03-05 10:53:17,844 [https-openssl-apr-443-exec-10 - https://itwiki.isaria-muc.com/bin/get/Main/3.%20Serverlandschaft/3.1%20Aufbau%20der%20Serverlandschaft%20/xx.xx%20Pexip%20Installation%20(Konferenzsystem)/?sheet=CKEditor.FileUploader&outputSyntax=plain&syntax=xwiki%2F2.1&language=de&form_token=DmTSuoJkk6pB0AH11iXgxA&initiator=filebrowser] ERROR c.x.x.w.Utils                  - Failed to process MultiPart request
com.xpn.xwiki.XWikiException: Error number 11008 in 11: Exception while getting uploaded files
        at com.xpn.xwiki.internal.fileupload.FileUploadUtils.getFileItems(FileUploadUtils.java:86)
        at com.xpn.xwiki.plugin.fileupload.FileUploadPlugin.loadFileList(FileUploadPlugin.java:213)
        at com.xpn.xwiki.plugin.fileupload.FileUploadPlugin.loadFileList(FileUploadPlugin.java:183)
        at com.xpn.xwiki.web.Utils.handleMultipart(Utils.java:614)
        at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:483)
        at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:258)
        at com.xpn.xwiki.web.LegacyActionServlet.service(LegacyActionServlet.java:104)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:733)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at com.xpn.xwiki.web.ActionFilter.doFilter(ActionFilter.java:122)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.xwiki.wysiwyg.filter.ConversionFilter.doFilter(ConversionFilter.java:109)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.xwiki.container.servlet.filters.internal.SetHTTPHeaderFilter.doFilter(SetHTTPHeaderFilter.java:63)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.xwiki.container.servlet.filters.internal.SavedRequestRestorerFilter.doFilter(SavedRequestRestorerFilter.java:208)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.xwiki.container.servlet.filters.internal.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:111)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.xwiki.resource.servlet.RoutingFilter.doFilter(RoutingFilter.java:132)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:544)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:143)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
        at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:698)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:353)
        at org.apache.coyote.http2.StreamProcessor.service(StreamProcessor.java:367)
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
        at org.apache.coyote.http2.StreamProcessor.process(StreamProcessor.java:71)
        at org.apache.coyote.http2.StreamRunnable.run(StreamRunnable.java:35)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.io.IOException: org.apache.tomcat.util.http.fileupload.impl.IOFileUploadException: Processing of multipart/form-data request failed. java.io.IOException: The socket [140,669,842,677,920] associated with this connection has been closed.
        at org.apache.catalina.connector.Request.parseParts(Request.java:3008)
        at org.apache.catalina.connector.Request.parseParameters(Request.java:3294)
        at org.apache.catalina.connector.Request.getParameterValues(Request.java:1233)
        at org.apache.catalina.connector.RequestFacade.getParameterValues(RequestFacade.java:424)
        at javax.servlet.ServletRequestWrapper.getParameterValues(ServletRequestWrapper.java:185)
        at org.xwiki.container.servlet.filters.internal.SavedRequestRestorerFilter$SavedRequestWrapper.getParameterValues(SavedRequestRestorerFilter.java:146)
        at org.xwiki.wysiwyg.filter.ConversionFilter.doFilter(ConversionFilter.java:91)
        ... 30 common frames omitted
Caused by: org.apache.tomcat.util.http.fileupload.impl.IOFileUploadException: Processing of multipart/form-data request failed. java.io.IOException: The socket [140,669,842,677,920] associated with this connection has been closed.
        at org.apache.tomcat.util.http.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:295)
        at org.apache.catalina.connector.Request.parseParts(Request.java:2960)
        ... 36 common frames omitted
Caused by: org.apache.catalina.connector.ClientAbortException: java.io.IOException: The socket [140,669,842,677,920] associated with this connection has been closed.
        at org.apache.catalina.connector.InputBuffer.realReadBytes(InputBuffer.java:348)
        at org.apache.catalina.connector.InputBuffer.checkByteBufferEof(InputBuffer.java:663)
        at org.apache.catalina.connector.InputBuffer.read(InputBuffer.java:370)
        at org.apache.catalina.connector.CoyoteInputStream.read(CoyoteInputStream.java:183)
        at org.apache.tomcat.util.http.fileupload.MultipartStream$ItemInputStream.makeAvailable(MultipartStream.java:975)
        at org.apache.tomcat.util.http.fileupload.MultipartStream$ItemInputStream.read(MultipartStream.java:879)
        at java.base/java.io.InputStream.read(InputStream.java:205)
        at org.apache.tomcat.util.http.fileupload.util.Streams.copy(Streams.java:98)
        at org.apache.tomcat.util.http.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:291)
        ... 37 common frames omitted
Caused by: java.io.IOException: The socket [140,669,842,677,920] associated with this connection has been closed.
        at org.apache.tomcat.util.net.AprEndpoint$AprSocketWrapper.doWrite(AprEndpoint.java:2339)
        at org.apache.tomcat.util.net.SocketWrapperBase.doWrite(SocketWrapperBase.java:716)
        at org.apache.tomcat.util.net.SocketWrapperBase.flushBlocking(SocketWrapperBase.java:669)
        at org.apache.tomcat.util.net.SocketWrapperBase.flush(SocketWrapperBase.java:659)
        at org.apache.coyote.http2.Http2UpgradeHandler.writeWindowUpdate(Http2UpgradeHandler.java:832)
        at org.apache.coyote.http2.Stream$StreamInputBuffer.doRead(Stream.java:1159)
        at org.apache.coyote.Request.doRead(Request.java:590)
        at org.apache.catalina.connector.InputBuffer.realReadBytes(InputBuffer.java:344)
        ... 45 common frames omitted

Anyone how konws how to solve?
Best regards
Martin