If the template_path setting is an unicode string and some template file contains non-ASCII characters, then tornado raises the following exception:
File "/home/venv/local/lib/python2.7/site-packages/tornado/template.py", line 633, in write_line
print(" " * indent + line + line_comment, file=self.file)
UnicodeDecodeError: 'ascii' codec can't decode byte 0xd0 in position 18: ordinal not in range(128)
Cause of the exception: the line variable is a str object containing non-ASCII characters and the line_comment variable is an unicode object.
Hello. See tiket #1027, it contains answer for this issue.