diff --git a/src/connections/pyserial.ts b/src/connections/pyserial.ts
index 911e4b4..ce1a013 100644
--- a/src/connections/pyserial.ts
+++ b/src/connections/pyserial.ts
@@ -125,7 +125,7 @@ export default class PySerial implements ConnectionTarget {
   }
 
   public async send(mssg: string, drain: boolean = true): Promise<void> {
-    let data = Buffer.from(mssg, 'binary');
+    let data = Buffer.from(mssg, 'utf8');
 
     await this.streamWrite(data);
 
diff --git a/src/rp2/sync.ts b/src/rp2/sync.ts
index bc786fa..61d653b 100644
--- a/src/rp2/sync.ts
+++ b/src/rp2/sync.ts
@@ -190,12 +190,12 @@ export default class Sync {
     await this.startSync(oncomplete, 'send', files);
   }
 
-  public async startReceive(oncomplete: Function, files: string) {
+  public async startReceive(oncomplete: Function, files?: string) {
     await this.settings.refresh();
     await this.startSync(oncomplete, 'receive', files);
   }
 
-  private async startSync(oncomplete: Function, method: string, files: string) {
+  private async startSync(oncomplete: Function, method: string, files?: string) {
     this.logger.info('Start sync method ' + method);
     this.fails = 0;
     this.method = method;
diff --git a/src/serialDolmatcher.ts b/src/serialDolmatcher.ts
index f192dbc..fbcd2fd 100644
--- a/src/serialDolmatcher.ts
+++ b/src/serialDolmatcher.ts
@@ -48,7 +48,7 @@ export default class SerialDolmatcher extends EventEmitter {
   private outputHidden: boolean;
   private status: number;
   private _fileSystems: any;
-  private syncObj: any;
+  private syncObj?: Sync;
   private ftpServer?: FtpSrv;
   private _fs?: FtpFileSystem;
   private firstTimeStart?: boolean;
@@ -479,7 +479,7 @@ export default class SerialDolmatcher extends EventEmitter {
       if (this.isSynchronizing()) {
         this.terminal?.writeln('An error occurred: ' + message);
         this.logger.warning('Synchronizing, stopping sync');
-        await this.syncObj.stop();
+        await this.syncObj?.stop();
       }
     } else {
       this.terminal?.writeln(
@@ -712,7 +712,7 @@ export default class SerialDolmatcher extends EventEmitter {
         await this.syncObj.startReceive(cb);
       } else {
         try {
-          await this.syncObj.startSend(cb, files);
+          await this.syncObj?.startSend(cb, files);
         } catch (e) {
           console.log(e);
         }
@@ -753,7 +753,7 @@ export default class SerialDolmatcher extends EventEmitter {
       let type = this.synchronizeType === 'receive' ? 'download' : 'upload';
       this.terminal?.writeln('Stopping ' + type + '....');
 
-      await this.syncObj.stop();
+      await this.syncObj?.stop();
       this.stopOperation();
     }
   }