diff --git a/app/src/main/java/io/legado/app/help/http/cronet/CronetHelper.kt b/app/src/main/java/io/legado/app/help/http/cronet/CronetHelper.kt
index b6d50f116..e47a4abfa 100644
--- a/app/src/main/java/io/legado/app/help/http/cronet/CronetHelper.kt
+++ b/app/src/main/java/io/legado/app/help/http/cronet/CronetHelper.kt
@@ -53,6 +53,8 @@ fun buildRequest(request: Request, callback: UrlRequest.Callback): UrlRequest {
         val contentType: MediaType? = requestBody.contentType()
         if (contentType != null) {
             requestBuilder.addHeader("Content-Type", contentType.toString())
+        } else {
+            requestBuilder.addHeader("Content-Type", "text/plain")
         }
         val buffer = Buffer()
         requestBody.writeTo(buffer)
diff --git a/app/src/main/java/io/legado/app/help/storage/BookWebDav.kt b/app/src/main/java/io/legado/app/help/storage/BookWebDav.kt
index 6147ff1db..cbdbd15ce 100644
--- a/app/src/main/java/io/legado/app/help/storage/BookWebDav.kt
+++ b/app/src/main/java/io/legado/app/help/storage/BookWebDav.kt
@@ -131,7 +131,7 @@ object BookWebDav {
                 WebDav(exportsWebDavUrl).makeAsDir()
                 // 如果导出的本地文件存在,开始上传
                 val putUrl = exportsWebDavUrl + fileName
-                WebDav(putUrl).upload(byteArray)
+                WebDav(putUrl).upload(byteArray, "text/plain")
             }
         } catch (e: Exception) {
             Handler(Looper.getMainLooper()).post {
@@ -153,7 +153,7 @@ object BookWebDav {
             val json = GSON.toJson(bookProgress)
             val url = getProgressUrl(book)
             if (initWebDav()) {
-                WebDav(url).upload(json.toByteArray())
+                WebDav(url).upload(json.toByteArray(), "application/json")
             }
         }
     }
diff --git a/app/src/main/java/io/legado/app/lib/webdav/WebDav.kt b/app/src/main/java/io/legado/app/lib/webdav/WebDav.kt
index e09b83c46..93e3752b2 100644
--- a/app/src/main/java/io/legado/app/lib/webdav/WebDav.kt
+++ b/app/src/main/java/io/legado/app/lib/webdav/WebDav.kt
@@ -185,11 +185,14 @@ class WebDav(urlStr: String) {
     /**
      * 上传文件
      */
-    suspend fun upload(localPath: String, contentType: String? = null): Boolean {
+    suspend fun upload(
+        localPath: String,
+        contentType: String = "application/octet-stream"
+    ): Boolean {
         val file = File(localPath)
         if (!file.exists()) return false
         // 务必注意RequestBody不要嵌套，不然上传时内容可能会被追加多余的文件信息
-        val fileBody = file.asRequestBody(contentType?.toMediaType())
+        val fileBody = file.asRequestBody(contentType.toMediaType())
         val url = httpUrl
         val auth = HttpAuth.auth
         if (url != null && auth != null) {
@@ -204,9 +207,9 @@ class WebDav(urlStr: String) {
         return false
     }
 
-    suspend fun upload(byteArray: ByteArray, contentType: String? = null): Boolean {
+    suspend fun upload(byteArray: ByteArray, contentType: String): Boolean {
         // 务必注意RequestBody不要嵌套，不然上传时内容可能会被追加多余的文件信息
-        val fileBody = byteArray.toRequestBody(contentType?.toMediaType())
+        val fileBody = byteArray.toRequestBody(contentType.toMediaType())
         val url = httpUrl
         val auth = HttpAuth.auth
         if (url != null && auth != null) {