Firefox

Enable Firefox Debug Logging at Runtime

  1. Go to about:networking
  2. Click Start Logging
  3. Copy the file name where it says it is writing to
  4. Reproduce the problem
  5. Click Stop Logging
  6. Review the file mentioned above

Enable Firefox Debug Logging at Startup

  1. Open terminal
  2. Set environment variables:
    • MOZ_LOG=timestamp,sync,rotate:200,nsHttp:5,cache2:5,nsSocketTransport:5,nsHostResolver:5,cookie:5
    • MOZ_LOG_FILE=/tmp/log.txt
  3. Start Firefox
  4. Reproduce the problem
  5. Review the file mentioned above

Source