diff --git a/attachments/nginx/ngx_module/ngx_cp_hook_threads.c b/attachments/nginx/ngx_module/ngx_cp_hook_threads.c
index 3896c9a..95911fc 100644
--- a/attachments/nginx/ngx_module/ngx_cp_hook_threads.c
+++ b/attachments/nginx/ngx_module/ngx_cp_hook_threads.c
@@ -271,7 +271,7 @@ ngx_http_cp_req_body_filter_thread(void *_ctx)
         if (fail_mode_verdict == NGX_OK) {
             THREAD_CTX_RETURN_NEXT_FILTER();
         }
-        THREAD_CTX_RETURN(NGX_ERROR);
+        THREAD_CTX_RETURN(NGX_HTTP_FORBIDDEN);
     }
     session_data_p->remaining_messages_to_reply += num_messages_sent;
 
@@ -308,7 +308,7 @@ ngx_http_cp_req_end_transaction_thread(void *_ctx)
         if (fail_mode_verdict == NGX_OK) {
             THREAD_CTX_RETURN_NEXT_FILTER();
         }
-        THREAD_CTX_RETURN(NGX_ERROR);
+        THREAD_CTX_RETURN(NGX_HTTP_FORBIDDEN);
     }
 
     session_data_p->remaining_messages_to_reply += num_messages_sent;
@@ -357,7 +357,7 @@ ngx_http_cp_res_header_filter_thread(void *_ctx)
         if (fail_mode_verdict == NGX_OK) {
             THREAD_CTX_RETURN_NEXT_FILTER();
         }
-        THREAD_CTX_RETURN(NGX_ERROR);
+        THREAD_CTX_RETURN(NGX_HTTP_FORBIDDEN);
     }
 
     session_data_p->remaining_messages_to_reply += num_messages_sent;
@@ -379,7 +379,7 @@ ngx_http_cp_res_header_filter_thread(void *_ctx)
         if (fail_mode_verdict == NGX_OK) {
             THREAD_CTX_RETURN_NEXT_FILTER();
         }
-        THREAD_CTX_RETURN(NGX_ERROR);
+        THREAD_CTX_RETURN(NGX_HTTP_FORBIDDEN);
     }
 
     session_data_p->remaining_messages_to_reply += num_messages_sent;
@@ -399,7 +399,7 @@ ngx_http_cp_res_header_filter_thread(void *_ctx)
         if (fail_mode_verdict == NGX_OK) {
             THREAD_CTX_RETURN_NEXT_FILTER();
         }
-        THREAD_CTX_RETURN(NGX_ERROR);
+        THREAD_CTX_RETURN(NGX_HTTP_FORBIDDEN);
     }
     session_data_p->response_data.new_compression_type = session_data_p->response_data.original_compression_type;
 
@@ -421,7 +421,7 @@ ngx_http_cp_res_header_filter_thread(void *_ctx)
         if (fail_mode_verdict == NGX_OK) {
             THREAD_CTX_RETURN_NEXT_FILTER();
         }
-        THREAD_CTX_RETURN(NGX_ERROR);
+        THREAD_CTX_RETURN(NGX_HTTP_FORBIDDEN);
     }
 
     session_data_p->remaining_messages_to_reply += num_messages_sent;
@@ -468,7 +468,7 @@ ngx_http_cp_res_body_filter_thread(void *_ctx)
         if (fail_mode_verdict == NGX_OK) {
             THREAD_CTX_RETURN_NEXT_FILTER();
         }
-        THREAD_CTX_RETURN(NGX_ERROR);
+        THREAD_CTX_RETURN(NGX_HTTP_FORBIDDEN);
     }
     session_data_p->remaining_messages_to_reply += num_messages_sent;
 
@@ -485,7 +485,7 @@ ngx_http_cp_res_body_filter_thread(void *_ctx)
             if (fail_mode_verdict == NGX_OK) {
                 THREAD_CTX_RETURN_NEXT_FILTER();
             }
-            THREAD_CTX_RETURN(NGX_ERROR);
+            THREAD_CTX_RETURN(NGX_HTTP_FORBIDDEN);
         }
         session_data_p->remaining_messages_to_reply++;
     }
@@ -523,7 +523,7 @@ ngx_http_cp_hold_verdict_thread(void *_ctx)
         if (fail_mode_hold_verdict == NGX_OK) {
             THREAD_CTX_RETURN_NEXT_FILTER();
         }
-        THREAD_CTX_RETURN(NGX_ERROR);
+        THREAD_CTX_RETURN(NGX_HTTP_FORBIDDEN);
     }
     session_data_p->remaining_messages_to_reply += num_messages_sent;
 
diff --git a/attachments/nginx/ngx_module/ngx_cp_hooks.c b/attachments/nginx/ngx_module/ngx_cp_hooks.c
index f7166ef..7cd83bc 100644
--- a/attachments/nginx/ngx_module/ngx_cp_hooks.c
+++ b/attachments/nginx/ngx_module/ngx_cp_hooks.c
@@ -600,7 +600,7 @@ ngx_http_cp_req_body_filter(ngx_http_request_t *request, ngx_chain_t *request_bo
             updateMetricField(MAX_REQ_BODY_SIZE_UPON_TIMEOUT, session_data_p->processed_req_body_size);
             updateMetricField(MIN_REQ_BODY_SIZE_UPON_TIMEOUT, session_data_p->processed_req_body_size);
 
-            return fail_mode_verdict == NGX_OK ? ngx_http_next_request_body_filter(request, request_body_chain) : NGX_ERROR;
+            return fail_mode_verdict == NGX_OK ? ngx_http_next_request_body_filter(request, request_body_chain) : NGX_HTTP_FORBIDDEN;
         }
         write_dbg(
             DBG_LEVEL_DEBUG,
@@ -615,7 +615,7 @@ ngx_http_cp_req_body_filter(ngx_http_request_t *request, ngx_chain_t *request_bo
             if (!res) {
                 session_data_p->verdict = fail_mode_hold_verdict == NGX_OK ? TRAFFIC_VERDICT_ACCEPT : TRAFFIC_VERDICT_DROP;
                 updateMetricField(HOLD_THREAD_TIMEOUT, 1);
-                return fail_mode_verdict == NGX_OK ? ngx_http_next_request_body_filter(request, request_body_chain) : NGX_ERROR;
+                return fail_mode_verdict == NGX_OK ? ngx_http_next_request_body_filter(request, request_body_chain) : NGX_HTTP_FORBIDDEN;
             }
         }
 
@@ -636,7 +636,7 @@ ngx_http_cp_req_body_filter(ngx_http_request_t *request, ngx_chain_t *request_bo
                     session_data_p->verdict == TRAFFIC_VERDICT_ACCEPT ? "accept" : "drop"
                 );
                 updateMetricField(REQ_BODY_THREAD_TIMEOUT, 1);
-                return fail_mode_verdict == NGX_OK ? ngx_http_next_request_body_filter(request, request_body_chain) : NGX_ERROR;
+                return fail_mode_verdict == NGX_OK ? ngx_http_next_request_body_filter(request, request_body_chain) : NGX_HTTP_FORBIDDEN;
             }
 
             write_dbg(
@@ -671,7 +671,7 @@ ngx_http_cp_req_body_filter(ngx_http_request_t *request, ngx_chain_t *request_bo
             session_data_p->session_id,
             session_data_p->verdict == TRAFFIC_VERDICT_ACCEPT ? "accept" : "drop"
         );
-        return fail_mode_verdict == NGX_OK ? ngx_http_next_request_body_filter(request, request_body_chain) : NGX_ERROR;
+        return fail_mode_verdict == NGX_OK ? ngx_http_next_request_body_filter(request, request_body_chain) : NGX_HTTP_FORBIDDEN;
     }
 
     final_res = ctx.res;
@@ -978,7 +978,7 @@ ngx_http_cp_res_body_filter(ngx_http_request_t *request, ngx_chain_t *body_chain
     if (was_transaction_timedout(session_data_p)) {
         // Session was timed out.
         if (session_data_p->verdict == TRAFFIC_VERDICT_DROP) {
-            return NGX_ERROR;
+            return NGX_HTTP_FORBIDDEN;
         }
         session_data_p->verdict = fail_mode_verdict == NGX_OK ? TRAFFIC_VERDICT_ACCEPT : TRAFFIC_VERDICT_DROP;
         fini_cp_session_data(session_data_p);
@@ -1041,7 +1041,7 @@ ngx_http_cp_res_body_filter(ngx_http_request_t *request, ngx_chain_t *body_chain
             if (fail_mode_verdict == NGX_OK) {
                 return ngx_http_next_response_body_filter(request, body_chain);
             }
-            return NGX_ERROR;
+            return NGX_HTTP_FORBIDDEN;
         }
         write_dbg(
             DBG_LEVEL_DEBUG,
@@ -1080,7 +1080,7 @@ ngx_http_cp_res_body_filter(ngx_http_request_t *request, ngx_chain_t *body_chain
         if (fail_mode_verdict == NGX_OK) {
             return ngx_http_next_response_body_filter(request, body_chain);
         }
-        return NGX_ERROR;
+        return NGX_HTTP_FORBIDDEN;
     }
 
     final_res = ctx.res;
@@ -1100,7 +1100,7 @@ ngx_http_cp_res_body_filter(ngx_http_request_t *request, ngx_chain_t *body_chain
         if (fail_mode_verdict == NGX_OK) {
             return ngx_http_next_response_body_filter(request, body_chain);
         }
-        return NGX_ERROR;
+        return NGX_HTTP_FORBIDDEN;
     }
 
     if (ctx.modifications) {
@@ -1112,7 +1112,7 @@ ngx_http_cp_res_body_filter(ngx_http_request_t *request, ngx_chain_t *body_chain
             if (fail_mode_verdict == NGX_OK) {
                 return ngx_http_next_response_body_filter(request, body_chain);
             }
-            return NGX_ERROR;
+            return NGX_HTTP_FORBIDDEN;
         }
     }
 
@@ -1148,7 +1148,7 @@ ngx_http_cp_res_body_filter(ngx_http_request_t *request, ngx_chain_t *body_chain
             fini_cp_session_data(session_data_p);
             return fail_mode_verdict == NGX_OK ?
                 ngx_http_next_response_body_filter(request, body_chain) :
-                NGX_ERROR;
+                NGX_HTTP_FORBIDDEN;
         }
     }
 
diff --git a/attachments/nginx/ngx_module/ngx_cp_initializer.c b/attachments/nginx/ngx_module/ngx_cp_initializer.c
index 8f17864..870837b 100644
--- a/attachments/nginx/ngx_module/ngx_cp_initializer.c
+++ b/attachments/nginx/ngx_module/ngx_cp_initializer.c
@@ -736,7 +736,6 @@ disconnect_communication()
     }
 
     set_need_registration(NOT_REGISTERED);
-    init_attachment_registration_thread();
 }
 
 ngx_int_t
diff --git a/attachments/nginx/ngx_module/ngx_cp_utils.c b/attachments/nginx/ngx_module/ngx_cp_utils.c
index fa34bc6..8d5c6aa 100644
--- a/attachments/nginx/ngx_module/ngx_cp_utils.c
+++ b/attachments/nginx/ngx_module/ngx_cp_utils.c
@@ -208,7 +208,7 @@ free_list_from_pool(ngx_pool_t *memory_pool, ngx_list_t *list)
 /// @param[in, out] key_list List of keys to add to the initialized hash table.
 /// @param[in] initial_data_value_ptr Initial data value pointer.
 /// @param[in] initial_data_size Initial data size that will be increased if necessary.
-/// @returns ngx_int_t 
+/// @returns ngx_int_t
 ///         - #NGX_OK.
 ///         - #NGX_ERROR.
 ///
@@ -407,7 +407,7 @@ split_chain_elem(ngx_chain_t *elem, uint16_t split_index, ngx_pool_t *pool)
 /// @param[in] data_size Size of the data to be put in NGINX chain.
 /// @param[in, out] data Data to put into the newly allocates NGINX chain.
 /// @param[in, out] pool NGINX pool to allocate buffers from.
-/// @returns 
+/// @returns
 ///
 ngx_chain_t *
 create_chain_elem(uint32_t data_size, char *data, ngx_pool_t *pool)
@@ -929,11 +929,11 @@ init_general_config(const char *conf_path)
     }
 
     // Setting fail open/close.
-    fail_mode_verdict = isFailOpenMode() == 1 ? NGX_OK : NGX_ERROR;
+    fail_mode_verdict = isFailOpenMode() == 1 ? NGX_OK : NGX_HTTP_FORBIDDEN;
     fail_open_timeout = getFailOpenTimeout();
 
     // Setting fail wait open/close
-    fail_mode_hold_verdict = isFailOpenHoldMode() == 1 ? NGX_OK : NGX_ERROR;
+    fail_mode_hold_verdict = isFailOpenHoldMode() == 1 ? NGX_OK : NGX_HTTP_FORBIDDEN;
     fail_open_hold_timeout = getFailOpenHoldTimeout();
 
     // Setting attachment's variables.