aiohttp rejects request — header exceeds 8190 bytes (max_field_size) after cookie accumulation

Summary

After significant matlab-proxy use, client headers seem to include a a large number of sessions in the cookies. Eventually this exceeds the 8190 bytes limit, and the matlab-proxy fails.

Inspecting the cookie sent from client to server includes 22x "matlab-proxy-session" cookies with 8410 bytes of cookie length, for a total header exceeding 9000 bytes.

Clearing browser cookies fixes this issue.

Relevant details:

• matlab-proxy: 0.34.0
• aiohttp: 3.14.3
• Python: 3.14.6
• MATLAB: R2025b
• Environment: containerized/pod, hostname changes per reboot, reverse tunneled to localhost

aiohttp.http_exceptions.LineTooLong: 400, message:
  Got more than 8190 bytes when reading: b'matlab-proxy-session-8af57f6f9b7920fa2aa0c900ebca276fba8cf025e82239b99ad45e5afa67528d="gAAAAABqhxL0t...'.
Error handling request from 127.0.0.1
Traceback (most recent call last):
  File "/home/user/.local/share/uv/tools/matlab-proxy/lib/python3.14/site-packages/aiohttp/web_protocol.py", line 433, in data_received
    messages, upgraded, tail = self._parser.feed_data(data)
                               ~~~~~~~~~~~~~~~~~~~~~~^^^^^^
  File "aiohttp/_http_parser.pyx", line 687, in aiohttp._http_parser.HttpParser.feed_data
    raise ex
  File "aiohttp/_http_parser.pyx", line 866, in aiohttp._http_parser.cb_on_header_value
    raise LineTooLong(value[:100] + b"...", pyparser._max_field_size)

Browser(s) used

Chrome

Script output

Not run