Fixes #3897

lib/core/subprocessng.py

@@ -13,6 +13,7 @@ import subprocess
 import time
 
 from lib.core.compat import buffer
+from lib.core.convert import getBytes
 from lib.core.settings import IS_WIN
 
 if IS_WIN:
@@ -192,6 +193,8 @@ def send_all(p, data):
     if not data:
         return
 
+    data = getBytes(data)
+
     while len(data):
         sent = p.send(data)
         if not isinstance(sent, int):