mod_proxy hangs when both KeepAlive and ProxyErrorOverride are enabled, and a non-200 response without a body is generated by the backend server. (e.g.: a client makes a request containing the "If-Modified-Since" and "If-None-Match" headers, to which the backend server respond with status 304.) Reproducible: Always Steps to Reproduce:
I committed this bug report to early - the fix is already in apache 2.0.52-r1