json解析时报错

Unexpected character ('<' (code 60)): expected a valid value (number, String, array, object, 'true', 'false' or 'null')
 at [Source: java.io.StringReader@33666bf5; line: 1, column: 2]
这是返回的json有问题，还是解析过程中出错？大部分都能够解析成功