# Buggy code
def _set_urlencoded_form(self, form_data):
    """
    Sets the body to the URL-encoded form data, and adds the appropriate content-type header.
    This will overwrite the existing content if there is one.
    """
    self.headers["content-type"] = "application/x-www-form-urlencoded"
    self.content = mitmproxy.net.http.url.encode(
        form_data, self.content.decode()
    ).encode()


# Traceback (UnicodeDecodeError)
Traceback (most recent call last):
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/master.py", line 216, in run
self.loop.run()
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/urwid/main_loop.py", line 278, in run
self._run()
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/urwid/main_loop.py", line 376, in _run
self.event_loop.run()
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/urwid/main_loop.py", line 682, in run
self._loop()
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/urwid/main_loop.py", line 719, in _loop
self._watch_files[fd]()
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/urwid/raw_display.py", line 393, in <lambda>
event_loop, callback, self.get_available_raw_input())
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/urwid/raw_display.py", line 493, in parse_input
callback(processed, processed_codes)
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/urwid/main_loop.py", line 403, in _update
self.process_input(keys)
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/urwid/main_loop.py", line 503, in process_input
k = self._topmost_widget.keypress(self.screen_size, k)
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/window.py", line 293, in keypress
k = super().keypress(size, k)
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/urwid/container.py", line 1128, in keypress
return self.body.keypress( (maxcol, remaining), key )
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/window.py", line 36, in keypress
ret = super().keypress(size, key)
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/urwid/container.py", line 1128, in keypress
return self.body.keypress( (maxcol, remaining), key )
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/urwid/container.py", line 592, in keypress
*self.calculate_padding_filler(size, True)), key)
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/overlay.py", line 130, in keypress
self.master.keymap.handle("global", key)
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/keymap.py", line 130, in handle
return self.executor(b.command)
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/commandexecutor.py", line 17, in __call__
ret = self.master.commands.call(cmd)
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/command.py", line 221, in call
return self.call_args(parts[0], parts[1:])
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/command.py", line 212, in call_args
return self.commands[path].call(args)
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/command.py", line 101, in call
ret = self.func(*pargs)
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/command.py", line 251, in wrapper
return function(*args, **kwargs)
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/consoleaddons.py", line 174, in nav_select
self.master.inject_key("m_select")
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/master.py", line 181, in inject_key
self.loop.process_input([key])
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/urwid/main_loop.py", line 503, in process_input
k = self._topmost_widget.keypress(self.screen_size, k)
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/window.py", line 293, in keypress
k = super().keypress(size, k)
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/urwid/container.py", line 1128, in keypress
return self.body.keypress( (maxcol, remaining), key )
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/window.py", line 36, in keypress
ret = super().keypress(size, key)
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/urwid/container.py", line 1128, in keypress
return self.body.keypress( (maxcol, remaining), key )
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/urwid/container.py", line 592, in keypress
*self.calculate_padding_filler(size, True)), key)
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/overlay.py", line 121, in keypress
signals.pop_view_state.send(self)
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/blinker/base.py", line 267, in send
for receiver in self.receivers_for(sender)]
File "/home/kajoj/Mitmproxy/mitmproxy/venv/lib/python3.5/site-packages/blinker/base.py", line 267, in <listcomp>
for receiver in self.receivers_for(sender)]
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/window.py", line 230, in pop
if self.focus_stack().pop():
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/window.py", line 98, in pop
self.call("layout_popping")
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/window.py", line 110, in call
getattr(self.top_window(), name)(*args, **kwargs)
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/grideditor/base.py", line 463, in layout_popping
self.call(self._w, "layout_popping")
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/grideditor/base.py", line 441, in call
f(*args, **kwargs)
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/grideditor/base.py", line 313, in layout_popping
self.callback(self.data_out(res), *self.cb_args, **self.cb_kwargs)
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/grideditor/base.py", line 456, in set_data_update
self.set_data(vals, flow)
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/tools/console/grideditor/editors.py", line 65, in set_data
flow.request.urlencoded_form = vals
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/net/http/request.py", line 462, in urlencoded_form
self._set_urlencoded_form(value)
File "/home/kajoj/Mitmproxy/mitmproxy/mitmproxy/net/http/request.py", line 444, in _set_urlencoded_form
self.content = mitmproxy.net.http.url.encode(form_data, self.content.decode()).encode()
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xa8 in position 0: invalid start byte

# Fixed code
def _set_urlencoded_form(self, form_data):
    """
    Sets the body to the URL-encoded form data, and adds the appropriate content-type header.
    This will overwrite the existing content if there is one.
    """
    self.headers["content-type"] = "application/x-www-form-urlencoded"
    self.content = mitmproxy.net.http.url.encode(
        form_data, self.get_text(strict=False)
    ).encode()