Problem to attach file after update

some user when want to attach file to documents get this error after update erpnext to last version
current version
ERPNext: v11.1.18 (master)

Frappe Framework: v11.1.18 (master)

any one know whats problem ? nothing change in access just after update erp this problem happened .

Traceback (most recent call last):
File “/home/frappe/frappe-bench/apps/frappe/frappe/”, line 61, in application
response = frappe.handler.handle()
File “/home/frappe/frappe-bench/apps/frappe/frappe/”, line 21, in handle
data = execute_cmd(cmd)
File “/home/frappe/frappe-bench/apps/frappe/frappe/”, line 56, in execute_cmd
return, **frappe.form_dict)
File “/home/frappe/frappe-bench/apps/frappe/frappe/”, line 1027, in call
return fn(*args, **newargs)
File “/home/frappe/frappe-bench/apps/frappe/frappe/”, line 125, in uploadfile
File “/home/frappe/frappe-bench/apps/frappe/frappe/”, line 277, in errprint
error_log.append({“exc”: msg, “locals”: get_frame_locals()})
File “/home/frappe/frappe-bench/apps/frappe/frappe/utils/”, line 211, in get_frame_locals
_locals.append(‘File “{}”, line {}, in {}\n{}’.format(filename, lineno, function, json.dumps(frame.f_locals, default=str, indent=4)))
File “/usr/lib/python2.7/json/”, line 250, in dumps
sort_keys=sort_keys, **kw).encode(obj)
File “/usr/lib/python2.7/json/”, line 209, in encode
chunks = list(chunks)
File “/usr/lib/python2.7/json/”, line 434, in _iterencode
for chunk in _iterencode_dict(o, _current_indent_level):
File “/usr/lib/python2.7/json/”, line 390, in _iterencode_dict
yield _encoder(value)
UnicodeDecodeError: ‘utf8’ codec can’t decode byte 0x82 in position 16: invalid start byte