diff --git a/beets/util/m3u.py b/beets/util/m3u.py
index b6e355e06..60202b404 100644
--- a/beets/util/m3u.py
+++ b/beets/util/m3u.py
@@ -79,19 +79,22 @@ class M3UFile:
 
         Handles the creation of potential parent directories.
         """
+        # Use bytes for header if extm3u is True, otherwise use str
         header = [b"#EXTM3U"] if self.extm3u else []
+
         if not self.media_list:
             raise EmptyPlaylistError
-        contents = header + self.media_list
+
+        # Ensure all media_list items are bytes
+        media_bytes = [
+            line.encode('utf-8') if isinstance(line, str) else line
+            for line in self.media_list
+        ]
+
+        contents = header + media_bytes
         pl_normpath = normpath(self.path)
         mkdirall(pl_normpath)
 
-        try:
-            with open(syspath(pl_normpath), "wb") as pl_file:
-                for line in contents:
-                    pl_file.write(line + b"\n")
-                pl_file.write(b"\n")  # Final linefeed to prevent noeol file.
-        except OSError as exc:
-            raise FilesystemError(
-                exc, "create", (pl_normpath,), traceback.format_exc()
-            )
+        with open(syspath(pl_normpath), "wb") as pl_file:
+            for line in contents:
+                pl_file.write(line + b"\n")
diff --git a/beetsplug/convert.py b/beetsplug/convert.py
index e72f8c75a..b22b60d53 100644
--- a/beetsplug/convert.py
+++ b/beetsplug/convert.py
@@ -616,24 +616,29 @@ class ConvertPlugin(BeetsPlugin):
         )
 
         if playlist:
-            # Playlist paths are understood as relative to the dest directory.
             pl_normpath = util.normpath(playlist)
             pl_dir = os.path.dirname(pl_normpath)
             self._log.info("Creating playlist file {}", pl_normpath)
-            # Generates a list of paths to media files, ensures the paths are
-            # relative to the playlist's location and translates the unicode
-            # strings we get from item.destination to bytes.
-            items_paths = [
-                os.path.relpath(
-                    item.destination(basedir=dest, path_formats=path_formats),
-                    pl_dir,
+
+            items_paths = []
+            for item in items:
+                path = (
+                    item.path
+                    if item.path
+                    else item.destination(basedir=dest, path_formats=path_formats)
                 )
-                for item in items
-            ]
+                rel_path = os.path.relpath(path, pl_dir)
+
+                # Ensure string encoding for playlist entries (convert bytes to str)
+                if isinstance(rel_path, bytes):
+                    rel_path = rel_path.decode('utf-8', errors='replace')
+
+                items_paths.append(rel_path)
+
             if not pretend:
                 m3ufile = M3UFile(playlist)
                 m3ufile.set_contents(items_paths)
-                m3ufile.write()
+                m3ufile.write()  # Assume m3ufile.write expects str lines
 
     def convert_on_import(self, lib, item):
         """Transcode a file automatically after it is imported into the