diff --git a/src/core/ngx_cycle.c b/src/core/ngx_cycle.c
index 47d5f56..63eec14 100644
--- a/src/core/ngx_cycle.c
+++ b/src/core/ngx_cycle.c
@@ -216,7 +216,7 @@
 
         if (module->create_conf) {
             rv = module->create_conf(cycle);
-            if (rv == NGX_CONF_ERROR) {
+            if (rv == NULL) {
                 ngx_destroy_pool(pool);
                 return NULL;
             }
diff --git a/src/event/modules/ngx_devpoll_module.c b/src/event/modules/ngx_devpoll_module.c
index 903efe6..6578862 100644
--- a/src/event/modules/ngx_devpoll_module.c
+++ b/src/event/modules/ngx_devpoll_module.c
@@ -550,7 +550,7 @@
 
     dpcf = ngx_palloc(cycle->pool, sizeof(ngx_devpoll_conf_t));
     if (dpcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     dpcf->changes = NGX_CONF_UNSET;
diff --git a/src/event/modules/ngx_epoll_module.c b/src/event/modules/ngx_epoll_module.c
index 71d8471..b3267b3 100644
--- a/src/event/modules/ngx_epoll_module.c
+++ b/src/event/modules/ngx_epoll_module.c
@@ -552,7 +552,7 @@
 
     epcf = ngx_palloc(cycle->pool, sizeof(ngx_epoll_conf_t));
     if (epcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     epcf->events = NGX_CONF_UNSET;
diff --git a/src/event/modules/ngx_eventport_module.c b/src/event/modules/ngx_eventport_module.c
index 4becf75..842d631 100644
--- a/src/event/modules/ngx_eventport_module.c
+++ b/src/event/modules/ngx_eventport_module.c
@@ -581,7 +581,7 @@
 
     epcf = ngx_palloc(cycle->pool, sizeof(ngx_eventport_conf_t));
     if (epcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     epcf->events = NGX_CONF_UNSET;
diff --git a/src/event/modules/ngx_kqueue_module.c b/src/event/modules/ngx_kqueue_module.c
index 1ad2d8d..a84fc8f 100644
--- a/src/event/modules/ngx_kqueue_module.c
+++ b/src/event/modules/ngx_kqueue_module.c
@@ -768,7 +768,7 @@
 
     kcf = ngx_palloc(cycle->pool, sizeof(ngx_kqueue_conf_t));
     if (kcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     kcf->changes = NGX_CONF_UNSET;
diff --git a/src/event/modules/ngx_rtsig_module.c b/src/event/modules/ngx_rtsig_module.c
index 6020936..926be0d 100644
--- a/src/event/modules/ngx_rtsig_module.c
+++ b/src/event/modules/ngx_rtsig_module.c
@@ -691,7 +691,7 @@
 
     rtscf = ngx_palloc(cycle->pool, sizeof(ngx_rtsig_conf_t));
     if (rtscf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     rtscf->signo = NGX_CONF_UNSET;
diff --git a/src/event/ngx_event.c b/src/event/ngx_event.c
index e30c563..7fc6901 100644
--- a/src/event/ngx_event.c
+++ b/src/event/ngx_event.c
@@ -1113,7 +1113,7 @@
 
     ecf = ngx_palloc(cycle->pool, sizeof(ngx_event_conf_t));
     if (ecf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     ecf->connections = NGX_CONF_UNSET_UINT;
@@ -1128,7 +1128,7 @@
     if (ngx_array_init(&ecf->debug_connection, cycle->pool, 4,
                        sizeof(ngx_event_debug_t)) == NGX_ERROR)
     {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
 #endif
diff --git a/src/event/ngx_event_openssl.c b/src/event/ngx_event_openssl.c
index 23a4fbe..1607814 100644
--- a/src/event/ngx_event_openssl.c
+++ b/src/event/ngx_event_openssl.c
@@ -2115,7 +2115,7 @@
 
     oscf = ngx_pcalloc(cycle->pool, sizeof(ngx_openssl_conf_t));
     if (oscf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_access_module.c b/src/http/modules/ngx_http_access_module.c
index 78b8a6a..405aad4 100644
--- a/src/http/modules/ngx_http_access_module.c
+++ b/src/http/modules/ngx_http_access_module.c
@@ -201,7 +201,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_access_loc_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     return conf;
diff --git a/src/http/modules/ngx_http_addition_filter_module.c b/src/http/modules/ngx_http_addition_filter_module.c
index eb6a4b1..4076c53 100644
--- a/src/http/modules/ngx_http_addition_filter_module.c
+++ b/src/http/modules/ngx_http_addition_filter_module.c
@@ -212,7 +212,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_addition_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_auth_basic_module.c b/src/http/modules/ngx_http_auth_basic_module.c
index 1d2d75e..c9ce694 100644
--- a/src/http/modules/ngx_http_auth_basic_module.c
+++ b/src/http/modules/ngx_http_auth_basic_module.c
@@ -372,7 +372,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_auth_basic_loc_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     return conf;
diff --git a/src/http/modules/ngx_http_autoindex_module.c b/src/http/modules/ngx_http_autoindex_module.c
index e6c1b1e..698b763 100644
--- a/src/http/modules/ngx_http_autoindex_module.c
+++ b/src/http/modules/ngx_http_autoindex_module.c
@@ -632,7 +632,7 @@
 
     conf = ngx_palloc(cf->pool, sizeof(ngx_http_autoindex_loc_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     conf->enable = NGX_CONF_UNSET;
diff --git a/src/http/modules/ngx_http_browser_module.c b/src/http/modules/ngx_http_browser_module.c
index e0710c1..d400fec 100644
--- a/src/http/modules/ngx_http_browser_module.c
+++ b/src/http/modules/ngx_http_browser_module.c
@@ -423,7 +423,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_browser_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_charset_filter_module.c b/src/http/modules/ngx_http_charset_filter_module.c
index 5f47ec6..a764991 100644
--- a/src/http/modules/ngx_http_charset_filter_module.c
+++ b/src/http/modules/ngx_http_charset_filter_module.c
@@ -1488,27 +1488,27 @@
 
     mcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_charset_main_conf_t));
     if (mcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     if (ngx_array_init(&mcf->charsets, cf->pool, 2, sizeof(ngx_http_charset_t))
         != NGX_OK)
     {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     if (ngx_array_init(&mcf->tables, cf->pool, 1,
                        sizeof(ngx_http_charset_tables_t))
         != NGX_OK)
     {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     if (ngx_array_init(&mcf->recodes, cf->pool, 2,
                        sizeof(ngx_http_charset_recode_t))
         != NGX_OK)
     {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     return mcf;
@@ -1522,7 +1522,7 @@
 
     lcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_charset_loc_conf_t));
     if (lcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_dav_module.c b/src/http/modules/ngx_http_dav_module.c
index 84a7672..7f53d54 100644
--- a/src/http/modules/ngx_http_dav_module.c
+++ b/src/http/modules/ngx_http_dav_module.c
@@ -1154,7 +1154,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_dav_loc_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_fastcgi_module.c b/src/http/modules/ngx_http_fastcgi_module.c
index 6064133..2373d7c 100644
--- a/src/http/modules/ngx_http_fastcgi_module.c
+++ b/src/http/modules/ngx_http_fastcgi_module.c
@@ -1833,7 +1833,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_fastcgi_loc_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_gzip_filter_module.c b/src/http/modules/ngx_http_gzip_filter_module.c
index 7c7ca0a..62b430b 100644
--- a/src/http/modules/ngx_http_gzip_filter_module.c
+++ b/src/http/modules/ngx_http_gzip_filter_module.c
@@ -1069,7 +1069,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_gzip_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_gzip_static_module.c b/src/http/modules/ngx_http_gzip_static_module.c
index 22e806a..19e4128 100644
--- a/src/http/modules/ngx_http_gzip_static_module.c
+++ b/src/http/modules/ngx_http_gzip_static_module.c
@@ -251,7 +251,7 @@
 
     conf = ngx_palloc(cf->pool, sizeof(ngx_http_gzip_static_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     conf->enable = NGX_CONF_UNSET;
diff --git a/src/http/modules/ngx_http_headers_filter_module.c b/src/http/modules/ngx_http_headers_filter_module.c
index 13cef0b..3b5ebd6 100644
--- a/src/http/modules/ngx_http_headers_filter_module.c
+++ b/src/http/modules/ngx_http_headers_filter_module.c
@@ -421,7 +421,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_headers_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_image_filter_module.c b/src/http/modules/ngx_http_image_filter_module.c
index 293a61f..b0e5fed 100644
--- a/src/http/modules/ngx_http_image_filter_module.c
+++ b/src/http/modules/ngx_http_image_filter_module.c
@@ -947,7 +947,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_image_filter_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     conf->filter = NGX_CONF_UNSET_UINT;
diff --git a/src/http/modules/ngx_http_index_module.c b/src/http/modules/ngx_http_index_module.c
index f88e599..d94fc11 100644
--- a/src/http/modules/ngx_http_index_module.c
+++ b/src/http/modules/ngx_http_index_module.c
@@ -366,7 +366,7 @@
 
     conf = ngx_palloc(cf->pool, sizeof(ngx_http_index_loc_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     conf->indices = NULL;
diff --git a/src/http/modules/ngx_http_limit_req_module.c b/src/http/modules/ngx_http_limit_req_module.c
index 3d20b29..2a07c74 100644
--- a/src/http/modules/ngx_http_limit_req_module.c
+++ b/src/http/modules/ngx_http_limit_req_module.c
@@ -522,7 +522,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_limit_req_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_limit_zone_module.c b/src/http/modules/ngx_http_limit_zone_module.c
index e11e081..95f07c6 100644
--- a/src/http/modules/ngx_http_limit_zone_module.c
+++ b/src/http/modules/ngx_http_limit_zone_module.c
@@ -381,7 +381,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_limit_zone_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_log_module.c b/src/http/modules/ngx_http_log_module.c
index efe720b..170e3a2 100644
--- a/src/http/modules/ngx_http_log_module.c
+++ b/src/http/modules/ngx_http_log_module.c
@@ -714,18 +714,18 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_log_main_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     if (ngx_array_init(&conf->formats, cf->pool, 4, sizeof(ngx_http_log_fmt_t))
         != NGX_OK)
     {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     fmt = ngx_array_push(&conf->formats);
     if (fmt == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     fmt->name.len = sizeof("combined") - 1;
@@ -735,7 +735,7 @@
 
     fmt->ops = ngx_array_create(cf->pool, 16, sizeof(ngx_http_log_op_t));
     if (fmt->ops == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     return conf;
@@ -749,7 +749,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_log_loc_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     conf->open_file_cache = NGX_CONF_UNSET_PTR;
diff --git a/src/http/modules/ngx_http_map_module.c b/src/http/modules/ngx_http_map_module.c
index d0eb02c..1f7786c 100644
--- a/src/http/modules/ngx_http_map_module.c
+++ b/src/http/modules/ngx_http_map_module.c
@@ -160,7 +160,7 @@
 
     mcf = ngx_palloc(cf->pool, sizeof(ngx_http_map_conf_t));
     if (mcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     mcf->hash_max_size = NGX_CONF_UNSET_UINT;
diff --git a/src/http/modules/ngx_http_memcached_module.c b/src/http/modules/ngx_http_memcached_module.c
index f68be1e..e613a20 100644
--- a/src/http/modules/ngx_http_memcached_module.c
+++ b/src/http/modules/ngx_http_memcached_module.c
@@ -513,7 +513,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_memcached_loc_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_proxy_module.c b/src/http/modules/ngx_http_proxy_module.c
index 132f7d1..6d73501 100644
--- a/src/http/modules/ngx_http_proxy_module.c
+++ b/src/http/modules/ngx_http_proxy_module.c
@@ -1883,7 +1883,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_proxy_loc_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_random_index_module.c b/src/http/modules/ngx_http_random_index_module.c
index 7ddb819..bb5544a 100644
--- a/src/http/modules/ngx_http_random_index_module.c
+++ b/src/http/modules/ngx_http_random_index_module.c
@@ -280,7 +280,7 @@
 
     conf = ngx_palloc(cf->pool, sizeof(ngx_http_random_index_loc_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     conf->enable = NGX_CONF_UNSET;
diff --git a/src/http/modules/ngx_http_realip_module.c b/src/http/modules/ngx_http_realip_module.c
index b069a1e..3b2cce6 100644
--- a/src/http/modules/ngx_http_realip_module.c
+++ b/src/http/modules/ngx_http_realip_module.c
@@ -360,7 +360,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_realip_loc_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_referer_module.c b/src/http/modules/ngx_http_referer_module.c
index 0582899..658f4a1 100644
--- a/src/http/modules/ngx_http_referer_module.c
+++ b/src/http/modules/ngx_http_referer_module.c
@@ -221,7 +221,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_referer_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
 #if (NGX_PCRE)
diff --git a/src/http/modules/ngx_http_rewrite_module.c b/src/http/modules/ngx_http_rewrite_module.c
index a848443..840c053 100644
--- a/src/http/modules/ngx_http_rewrite_module.c
+++ b/src/http/modules/ngx_http_rewrite_module.c
@@ -220,7 +220,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_rewrite_loc_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     conf->stack_size = NGX_CONF_UNSET_UINT;
diff --git a/src/http/modules/ngx_http_secure_link_module.c b/src/http/modules/ngx_http_secure_link_module.c
index 049a45c..2f9351d 100644
--- a/src/http/modules/ngx_http_secure_link_module.c
+++ b/src/http/modules/ngx_http_secure_link_module.c
@@ -152,7 +152,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_secure_link_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_ssi_filter_module.c b/src/http/modules/ngx_http_ssi_filter_module.c
index d27d854..97b58fa 100644
--- a/src/http/modules/ngx_http_ssi_filter_module.c
+++ b/src/http/modules/ngx_http_ssi_filter_module.c
@@ -2689,14 +2689,14 @@
 
     smcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_ssi_main_conf_t));
     if (smcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     smcf->commands.pool = cf->pool;
     smcf->commands.temp_pool = cf->temp_pool;
 
     if (ngx_hash_keys_array_init(&smcf->commands, NGX_HASH_SMALL) != NGX_OK) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     return smcf;
@@ -2736,7 +2736,7 @@
 
     slcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_ssi_loc_conf_t));
     if (slcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_ssl_module.c b/src/http/modules/ngx_http_ssl_module.c
index 3bf52a2..c0fd6fd 100644
--- a/src/http/modules/ngx_http_ssl_module.c
+++ b/src/http/modules/ngx_http_ssl_module.c
@@ -302,7 +302,7 @@
 
     sscf = ngx_pcalloc(cf->pool, sizeof(ngx_http_ssl_srv_conf_t));
     if (sscf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_sub_filter_module.c b/src/http/modules/ngx_http_sub_filter_module.c
index 34f3294..9f07881 100644
--- a/src/http/modules/ngx_http_sub_filter_module.c
+++ b/src/http/modules/ngx_http_sub_filter_module.c
@@ -638,7 +638,7 @@
 
     slcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_sub_loc_conf_t));
     if (slcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_userid_filter_module.c b/src/http/modules/ngx_http_userid_filter_module.c
index 3462f64..9997274 100644
--- a/src/http/modules/ngx_http_userid_filter_module.c
+++ b/src/http/modules/ngx_http_userid_filter_module.c
@@ -570,7 +570,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_userid_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/ngx_http_xslt_filter_module.c b/src/http/modules/ngx_http_xslt_filter_module.c
index ab3118f..87828f9 100644
--- a/src/http/modules/ngx_http_xslt_filter_module.c
+++ b/src/http/modules/ngx_http_xslt_filter_module.c
@@ -1169,7 +1169,7 @@
 
     conf = ngx_palloc(cf->pool, sizeof(ngx_http_xslt_filter_main_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     if (ngx_array_init(&conf->dtd_files, cf->pool, 1,
@@ -1197,7 +1197,7 @@
 
     conf = ngx_pcalloc(cf->pool, sizeof(ngx_http_xslt_filter_loc_conf_t));
     if (conf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/modules/perl/ngx_http_perl_module.c b/src/http/modules/perl/ngx_http_perl_module.c
index e22428a..4409e8f 100644
--- a/src/http/modules/perl/ngx_http_perl_module.c
+++ b/src/http/modules/perl/ngx_http_perl_module.c
@@ -784,7 +784,7 @@
 
     pmcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_perl_main_conf_t));
     if (pmcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     if (ngx_array_init(&pmcf->requires, cf->pool, 1, sizeof(u_char *))
@@ -869,7 +869,7 @@
 
     plcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_perl_loc_conf_t));
     if (plcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/ngx_http_core_module.c b/src/http/ngx_http_core_module.c
index e2f7b86..3d2ccd0 100644
--- a/src/http/ngx_http_core_module.c
+++ b/src/http/ngx_http_core_module.c
@@ -2703,14 +2703,14 @@
 
     cmcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_core_main_conf_t));
     if (cmcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     if (ngx_array_init(&cmcf->servers, cf->pool, 4,
                        sizeof(ngx_http_core_srv_conf_t *))
         != NGX_OK)
     {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     cmcf->server_names_hash_max_size = NGX_CONF_UNSET_UINT;
@@ -2762,7 +2762,7 @@
 
     cscf = ngx_pcalloc(cf->pool, sizeof(ngx_http_core_srv_conf_t));
     if (cscf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
@@ -2775,14 +2775,14 @@
                        sizeof(ngx_http_listen_t))
         != NGX_OK)
     {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     if (ngx_array_init(&cscf->server_names, cf->temp_pool, 4,
                        sizeof(ngx_http_server_name_t))
         != NGX_OK)
     {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     cscf->connection_pool_size = NGX_CONF_UNSET_SIZE;
@@ -2893,7 +2893,7 @@
 
     lcf = ngx_pcalloc(cf->pool, sizeof(ngx_http_core_loc_conf_t));
     if (lcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*
diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
index eb839e1..1d9ccb8 100644
--- a/src/http/ngx_http_upstream.c
+++ b/src/http/ngx_http_upstream.c
@@ -4182,7 +4182,7 @@
                        sizeof(ngx_http_upstream_srv_conf_t *))
         != NGX_OK)
     {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     return umcf;
diff --git a/src/mail/ngx_mail_auth_http_module.c b/src/mail/ngx_mail_auth_http_module.c
index f7ad308..acd0665 100644
--- a/src/mail/ngx_mail_auth_http_module.c
+++ b/src/mail/ngx_mail_auth_http_module.c
@@ -1302,7 +1302,7 @@
 
     ahcf = ngx_pcalloc(cf->pool, sizeof(ngx_mail_auth_http_conf_t));
     if (ahcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     ahcf->timeout = NGX_CONF_UNSET_MSEC;
diff --git a/src/mail/ngx_mail_core_module.c b/src/mail/ngx_mail_core_module.c
index d0addb0..bd2c916 100644
--- a/src/mail/ngx_mail_core_module.c
+++ b/src/mail/ngx_mail_core_module.c
@@ -120,20 +120,20 @@
 
     cmcf = ngx_pcalloc(cf->pool, sizeof(ngx_mail_core_main_conf_t));
     if (cmcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     if (ngx_array_init(&cmcf->servers, cf->pool, 4,
                        sizeof(ngx_mail_core_srv_conf_t *))
         != NGX_OK)
     {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     if (ngx_array_init(&cmcf->listen, cf->pool, 4, sizeof(ngx_mail_listen_t))
         != NGX_OK)
     {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     return cmcf;
diff --git a/src/mail/ngx_mail_proxy_module.c b/src/mail/ngx_mail_proxy_module.c
index 193df8a..b408ed7 100644
--- a/src/mail/ngx_mail_proxy_module.c
+++ b/src/mail/ngx_mail_proxy_module.c
@@ -1061,7 +1061,7 @@
 
     pcf = ngx_pcalloc(cf->pool, sizeof(ngx_mail_proxy_conf_t));
     if (pcf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     pcf->enable = NGX_CONF_UNSET;
diff --git a/src/mail/ngx_mail_ssl_module.c b/src/mail/ngx_mail_ssl_module.c
index 4e2bda5..1fcdb75 100644
--- a/src/mail/ngx_mail_ssl_module.c
+++ b/src/mail/ngx_mail_ssl_module.c
@@ -166,7 +166,7 @@
 
     scf = ngx_pcalloc(cf->pool, sizeof(ngx_mail_ssl_conf_t));
     if (scf == NULL) {
-        return NGX_CONF_ERROR;
+        return NULL;
     }
 
     /*