cache management portal failing with error: CSP application closed the connection before sending a complete response

I can start cache without issue. There are no errors in the console log. However, when I access the management portal the page fails to display instead displaying the error page with the error "CSP application closed the connection before sending a complete response". This was working yesterday so the root cause is not clear. Reviewing all log files, the only error I have found is in the csp.log. The error is:

>>> Time: Mon Sep 20 06:54:19 2021; RT Build: 1801.1632a (win32/apapi:srv=2.4.20/apr=1.5.2/apu=1.5.4/mpm=WinNT); Log-Level: 6; Gateway-PID: 15516; Gateway-TID: 10232; Connection-No: 0; Server: LOCAL; Cache-PID: 0; Request-ID: 1; Session-ID: ACYxhzwgxw; Remote-Addr: ::1; Page: GET /csp/sys/UtilHome.csp
    WARNING: Corrupt Buffer Header returned from Cache: 65:53:50:3a (101:83:80:58), total = 978342757

I don't understand what has occurred or how to correct the condition.