diff --git a/src/http/modules/ngx_http_fastcgi_module.c b/src/http/modules/ngx_http_fastcgi_module.c
index 69ac0f7..4a8dc33 100644
--- a/src/http/modules/ngx_http_fastcgi_module.c
+++ b/src/http/modules/ngx_http_fastcgi_module.c
@@ -2021,7 +2021,7 @@
 
             /* rc == NGX_HTTP_PARSE_INVALID_HEADER */
 
-            ngx_log_error(NGX_LOG_INFO, r->connection->log, 0,
+            ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                           "upstream sent invalid header: \"%*s\\x%02xd...\"",
                           r->header_end - r->header_name_start,
                           r->header_name_start, *r->header_end);
diff --git a/src/http/modules/ngx_http_proxy_module.c b/src/http/modules/ngx_http_proxy_module.c
index a5cc27b..7c4061c 100644
--- a/src/http/modules/ngx_http_proxy_module.c
+++ b/src/http/modules/ngx_http_proxy_module.c
@@ -2021,7 +2021,7 @@
 
         /* rc == NGX_HTTP_PARSE_INVALID_HEADER */
 
-        ngx_log_error(NGX_LOG_INFO, r->connection->log, 0,
+        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                       "upstream sent invalid header: \"%*s\\x%02xd...\"",
                       r->header_end - r->header_name_start,
                       r->header_name_start, *r->header_end);
diff --git a/src/http/modules/ngx_http_scgi_module.c b/src/http/modules/ngx_http_scgi_module.c
index 570713d..e5d31ae 100644
--- a/src/http/modules/ngx_http_scgi_module.c
+++ b/src/http/modules/ngx_http_scgi_module.c
@@ -1142,7 +1142,7 @@
 
         /* rc == NGX_HTTP_PARSE_INVALID_HEADER */
 
-        ngx_log_error(NGX_LOG_INFO, r->connection->log, 0,
+        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                       "upstream sent invalid header: \"%*s\\x%02xd...\"",
                       r->header_end - r->header_name_start,
                       r->header_name_start, *r->header_end);
diff --git a/src/http/modules/ngx_http_uwsgi_module.c b/src/http/modules/ngx_http_uwsgi_module.c
index 4f9c349..d46741a 100644
--- a/src/http/modules/ngx_http_uwsgi_module.c
+++ b/src/http/modules/ngx_http_uwsgi_module.c
@@ -1363,7 +1363,7 @@
 
         /* rc == NGX_HTTP_PARSE_INVALID_HEADER */
 
-        ngx_log_error(NGX_LOG_INFO, r->connection->log, 0,
+        ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                       "upstream sent invalid header: \"%*s\\x%02xd...\"",
                       r->header_end - r->header_name_start,
                       r->header_name_start, *r->header_end);