diff --git a/dist/index.cjs.js b/dist/index.cjs.js
index 7b7d62c..04048df 100644
--- a/dist/index.cjs.js
+++ b/dist/index.cjs.js
@@ -175,11 +175,12 @@ class Updater {
     }
     async sendNextPacket() {
         let packet = this.file.slice(this._fileProgress, this._fileProgress + this._packetSize);
+        this._fileProgress += this._packetSize;
         return new Promise((resolve, reject) => {
             this.bleObject.write(this.bleDeviceId, this._updaterServiceUUID, this._updateFileCharacteristicUUID, packet.buffer, () => {
-                this._fileProgress += this._packetSize;
                 resolve(true);
             }, (error) => {
+                this._fileProgress -= this._packetSize;
                 reject(error);
             });
         });
diff --git a/dist/index.es.js b/dist/index.es.js
index 97c7544..be84531 100644
--- a/dist/index.es.js
+++ b/dist/index.es.js
@@ -173,11 +173,12 @@ class Updater {
     }
     async sendNextPacket() {
         let packet = this.file.slice(this._fileProgress, this._fileProgress + this._packetSize);
+        this._fileProgress += this._packetSize;
         return new Promise((resolve, reject) => {
             this.bleObject.write(this.bleDeviceId, this._updaterServiceUUID, this._updateFileCharacteristicUUID, packet.buffer, () => {
-                this._fileProgress += this._packetSize;
                 resolve(true);
             }, (error) => {
+                this._fileProgress -= this._packetSize;
                 reject(error);
             });
         });
diff --git a/package.json b/package.json
index e1f82e1..1004479 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "updaterweblibrary",
-  "version": "1.0.19",
+  "version": "1.0.20",
   "description": "OTA Updater App frontend library",
   "repository": {
     "type": "git",