Tomcat执行一段时间后报错

Tomcat执行一段时间后报如下错误：
27-Jun-2016 08:52:59.217 INFO [http-nio-80-exec-3] org.apache.coyote.http11.AbstractHttp11Processor.process Error parsing HTTP request header
Note: further occurrences of HTTP header parsing errors will be logged at DEBUG level.
java.lang.IllegalArgumentException: Invalid character found in method name. HTTP method names must be tokens
at org.apache.coyote.http11.AbstractNioInputBuffer.parseRequestLine(AbstractNioInputBuffer.java:232)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1013)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:670)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1520)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1476)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)

根据要求，配置server.xml文件，加大maxHttpHeaderSize值，无效