diff --git a/app/src/main/java/io/legado/app/model/localBook/LocalBook.kt b/app/src/main/java/io/legado/app/model/localBook/LocalBook.kt
index 1dd42cf43..2714be657 100644
--- a/app/src/main/java/io/legado/app/model/localBook/LocalBook.kt
+++ b/app/src/main/java/io/legado/app/model/localBook/LocalBook.kt
@@ -388,7 +388,7 @@ object LocalBook {
     //下载book对应的远程文件 并更新Book
     private fun downloadRemoteBook(localBook: Book) {
         val webDavUrl = localBook.getRemoteUrl()
-        if (webDavUrl.isNullOrBlank()) return null
+        if (webDavUrl.isNullOrBlank()) throw NoStackTraceException("Book file is not webDav File")
         try {
             AppConfig.defaultBookTreeUri
                 ?: throw NoBooksDirException()