求高手指教

程序中抛出
org.codehaus.jackson.JsonParseException: Unexpected character ('<' (code 60)): expected a valid value (number, String, array, object, 'true', 'false' or 'null')
 at [Source: java.io.StringReader@299e34; line: 1, column: 2]
at org.codehaus.jackson.JsonParser._constructError(JsonParser.java:943)
at org.codehaus.jackson.impl.JsonParserBase._reportError(JsonParserBase.java:632)
at org.codehaus.jackson.impl.JsonParserBase._reportUnexpectedChar(JsonParserBase.java:565)
at org.codehaus.jackson.impl.ReaderBasedParser._handleUnexpectedValue(ReaderBasedParser.java:429)
at org.codehaus.jackson.impl.ReaderBasedParser.nextToken(ReaderBasedParser.java:192)
at org.codehaus.jackson.map.ObjectMapper._initForReading(ObjectMapper.java:1625)
at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:1580)
at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1116)
at com.linkage.portal.serviceclient.json.JasonToBean.jason2bean(JasonToBean.java:18)
at com.linkage.portal.serviceclient.impl.HttpServcieCall.callServcie(HttpServcieCall.java:37)
at com.linkage.portal.serviceclient.ServiceCall.call(ServiceCall.java:17)
at com.linkage.portal.common.DataBusFactory.dataBusServiceDB(DataBusFactory.java:37)

出现之后，重启下weblogic中该节点的服务就又好了，十分奇怪，有没有人遇到过类似问题？恳请指教一二