--- a/doc/tools/pyjsrest.py	Tue Dec 10 17:14:56 2019 +0100
+++ b/doc/tools/pyjsrest.py	Tue Dec 10 23:34:46 2019 +0100
@@ -89,7 +89,7 @@
             index.add(filename)
             # save rst file
             with open(osp.join(rst_dir, filename) + '.rst', 'wb') as f_rst:
-                f_rst.write(rst_content)
+                f_rst.write(rst_content.encode())
     stream = open(osp.join(rst_dir, 'index.rst'), 'w')
     stream.write('''
 Javascript API