PHP and mod_fcgid: ap_pass_brigade failed in handle_request_ipc function

The warning has nothing to do with any of the Fcgidxxx options and is simply caused by client’s closing their side of the connection before the server gets a chance to respond.

From the actual source:

/* Now pass any remaining response body data to output filters */
if ((rv = ap_pass_brigade(r->output_filters, brigade_stdout)) != APR_SUCCESS) {
    if (!APR_STATUS_IS_ECONNABORTED(rv)) {
        ap_log_rerror(APLOG_MARK, APLOG_WARNING, rv, r,
                      "mod_fcgid: ap_pass_brigade failed in "
                      "handle_request_ipc function");
    }

    return HTTP_INTERNAL_SERVER_ERROR;
}

Credit goes to Avian’s Blog who found out about it.