...

examcloud-core-examwork-api-provider/src/main/java/cn/com/qmth/examcloud/core/examwork/api/provider/ExamStudentCloudServiceProvider.java

@@ -75,7 +75,9 @@ public class ExamStudentCloudServiceProvider extends ControllerSupport
 	public SaveExamStudentResp saveExamStudent(@RequestBody SaveExamStudentReq req) {
 
 		String paperType = req.getPaperType();
-		if (!paperType.matches("[A-Z]")) {
+		if (StringUtils.isBlank(paperType)) {
+			paperType = "A";
+		} else if (!paperType.matches("[A-Z]")) {
 			throw new StatusException("E-100020", "paperType must be one of A-Z");
 		}