Python Exception Occurred

Traceback (most recent call last):
  File "/var/www/localhost/viewcvs/lib/viewcvs.py", line 2640, in run_cgi
    main()
  File "/var/www/localhost/viewcvs/lib/viewcvs.py", line 2604, in main
    view_checkout(request)
  File "/var/www/localhost/viewcvs/lib/viewcvs.py", line 1923, in view_checkout
    request.mime_type)
  File "/var/www/localhost/viewcvs/lib/viewcvs.py", line 1857, in process_checkout
    raise 'illegal value for content-type parameter'
illegal value for content-type parameter