A large post request fails with "UT000020: Connection terminated as request was larger than ###" in JBoss EAP 7.x

Issue

• We see an exception like the following:

Caused by: java.io.IOException: UT000020: Connection terminated as request was larger than 10485760
    at io.undertow.server.protocol.ajp.AjpServerRequestConduit.doRead(AjpServerRequestConduit.java:289)
    at io.undertow.server.protocol.ajp.AjpServerRequestConduit.read(AjpServerRequestConduit.java:199)
    at org.xnio.conduits.ConduitStreamSourceChannel.read(ConduitStreamSourceChannel.java:127)

• We have a fileupload application and a request fails with the following exception when uploading a large file:

ERROR [io.undertow.request] (default task-3) UT005023: Exception handling request to /jboss-servlet-commons-fileupload/upload: javax.servlet.ServletException: org.apache.commons.fileupload.FileUploadException: UT000020: Connection terminated as request was larger than 10485760
    at org.jboss.as.quickstart.upload.CommonsFileUploadServlet.doPost(CommonsFileUploadServlet.java:99)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
    at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:85)
    at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
    at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
    at org.wildfly.extension.undertow.security.SecurityContextAssociationHandler.handleRequest(SecurityContextAssociationHandler.java:78)
    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:131)
    at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)
    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
    at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
    at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:60)
    at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:77)
    at io.undertow.security.handlers.NotificationReceiverHandler.handleRequest(NotificationReceiverHandler.java:50)
    at io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43)
    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at org.wildfly.extension.undertow.security.jacc.JACCContextIdHandler.handleRequest(JACCContextIdHandler.java:61)
    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
    at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:285)
    at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:264)
    at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:81)
    at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:175)
    at io.undertow.server.Connectors.executeRootHandler(Connectors.java:324)
    at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:803)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)
Caused by: org.apache.commons.fileupload.FileUploadException: UT000020: Connection terminated as request was larger than 10485760
    at org.apache.commons.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:362)
    at org.apache.commons.fileupload.servlet.ServletFileUpload.parseRequest(ServletFileUpload.java:115)
    at org.jboss.as.quickstart.upload.CommonsFileUploadServlet.doPost(CommonsFileUploadServlet.java:81)
    ... 29 more
Caused by: java.io.IOException: UT000020: Connection terminated as request was larger than 10485760
    at io.undertow.conduits.FixedLengthStreamSourceConduit.checkMaxSize(FixedLengthStreamSourceConduit.java:168)
    at io.undertow.conduits.FixedLengthStreamSourceConduit.read(FixedLengthStreamSourceConduit.java:229)
    at org.xnio.conduits.ConduitStreamSourceChannel.read(ConduitStreamSourceChannel.java:127)
    at io.undertow.channels.DetachableStreamSourceChannel.read(DetachableStreamSourceChannel.java:209)
    at io.undertow.server.HttpServerExchange$ReadDispatchChannel.read(HttpServerExchange.java:2270)
    at org.xnio.channels.Channels.readBlocking(Channels.java:294)
    at io.undertow.servlet.spec.ServletInputStreamImpl.readIntoBuffer(ServletInputStreamImpl.java:170)
    at io.undertow.servlet.spec.ServletInputStreamImpl.read(ServletInputStreamImpl.java:146)
    at org.apache.commons.fileupload.MultipartStream$ItemInputStream.makeAvailable(MultipartStream.java:999)
    at org.apache.commons.fileupload.MultipartStream$ItemInputStream.read(MultipartStream.java:903)
    at java.io.InputStream.read(InputStream.java:101)
    at org.apache.commons.fileupload.util.Streams.copy(Streams.java:100)
    at org.apache.commons.fileupload.util.Streams.copy(Streams.java:70)
    at org.apache.commons.fileupload.MultipartStream.readBodyData(MultipartStream.java:593)
    at org.apache.commons.fileupload.MultipartStream.discardBodyData(MultipartStream.java:617)
    at org.apache.commons.fileupload.MultipartStream.skipPreamble(MultipartStream.java:634)
    at org.apache.commons.fileupload.FileUploadBase$FileItemIteratorImpl.findNextItem(FileUploadBase.java:1023)
    at org.apache.commons.fileupload.FileUploadBase$FileItemIteratorImpl.<init>(FileUploadBase.java:1003)
    at org.apache.commons.fileupload.FileUploadBase.getItemIterator(FileUploadBase.java:310)
    at org.apache.commons.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:334)
    ... 31 more