diff --git a/filter/cache_storage.go b/filter/cache_storage.go
index 4a418ccb4..077c5839d 100644
--- a/filter/cache_storage.go
+++ b/filter/cache_storage.go
@@ -44,6 +44,7 @@ func NewCacheStorage(logger moira.Logger, metrics *metrics.FilterMetrics, reader
 	if err := storage.buildRetentions(bufio.NewScanner(reader)); err != nil {
 		return nil, err
 	}
+
 	return storage, nil
 }
 
@@ -63,6 +64,7 @@ func (storage *Storage) getRetention(m *moira.MatchedMetric) int {
 	if item, ok := storage.retentionsCache[m.Metric]; ok && item.timestamp+60 > m.Timestamp {
 		return item.value
 	}
+
 	for _, matcher := range storage.retentions {
 		if matcher.pattern.MatchString(m.Metric) {
 			storage.retentionsCache[m.Metric] = &retentionCacheItem{
@@ -72,6 +74,7 @@ func (storage *Storage) getRetention(m *moira.MatchedMetric) int {
 			return matcher.retention
 		}
 	}
+
 	return defaultRetention
 }
 
@@ -98,6 +101,7 @@ func (storage *Storage) buildRetentions(retentionScanner *bufio.Scanner) error {
 			storage.logger.Error().
 				String("pattern", patternString).
 				Msg("Invalid pattern found")
+
 			continue
 		}
 
@@ -112,6 +116,7 @@ func (storage *Storage) buildRetentions(retentionScanner *bufio.Scanner) error {
 			retention: retention,
 		})
 	}
+
 	return retentionScanner.Err()
 }
 
diff --git a/filter/connection/listening.go b/filter/connection/listening.go
index 8f707edae..ae246a6c3 100644
--- a/filter/connection/listening.go
+++ b/filter/connection/listening.go
@@ -25,18 +25,21 @@ type MetricsListener struct {
 func NewListener(port string, logger moira.Logger, metrics *metrics.FilterMetrics) (*MetricsListener, error) {
 	address, err := net.ResolveTCPAddr("tcp", port)
 	if nil != err {
-		return nil, fmt.Errorf("failed to resolve tcp address [%s]: %s", port, err.Error())
+		return nil, fmt.Errorf("failed to resolve tcp address [%s]: %w", port, err)
 	}
+
 	newListener, err := net.ListenTCP("tcp", address)
 	if err != nil {
-		return nil, fmt.Errorf("failed to listen on [%s]: %s", port, err.Error())
+		return nil, fmt.Errorf("failed to listen on [%s]: %w", port, err)
 	}
+
 	listener := MetricsListener{
 		listener: newListener,
 		logger:   logger,
 		handler:  NewConnectionsHandler(logger),
 		metrics:  metrics,
 	}
+
 	return &listener, nil
 }
 
@@ -58,6 +61,7 @@ func (listener *MetricsListener) Listen() chan []byte {
 				}
 			default:
 			}
+
 			listener.listener.SetDeadline(time.Now().Add(1e9)) //nolint
 			conn, err := listener.listener.Accept()
 			if nil != err {
@@ -65,20 +69,23 @@ func (listener *MetricsListener) Listen() chan []byte {
 				if ok := errors.As(err, &opErr); ok && opErr.Timeout() {
 					continue
 				}
-				listener.logger.Info().
+				listener.logger.Error().
 					Error(err).
 					Msg("Failed to accept connection")
 				continue
 			}
+
 			listener.logger.Info().
 				String("remote_address", conn.RemoteAddr().String()).
-				Msg("Someone connected")
+				Msg("Successfully connected")
 
 			listener.handler.HandleConnection(conn, lineChan)
 		}
 	})
+
 	listener.tomb.Go(func() error { return listener.checkNewLinesChannelLen(lineChan) })
 	listener.logger.Info().Msg("Moira Filter Listener Started")
+
 	return lineChan
 }
 
diff --git a/filter/heartbeat/worker.go b/filter/heartbeat/worker.go
index bcf0cd340..b1332c19f 100644
--- a/filter/heartbeat/worker.go
+++ b/filter/heartbeat/worker.go
@@ -39,22 +39,23 @@ func (worker *Worker) Start() {
 			case <-checkTicker.C:
 				newCount := worker.metrics.TotalMetricsReceived.Count()
 				if newCount != count {
-					worker.logger.Debug().
-						Int64("from", count).
-						Int64("to", newCount).
-						Msg("Heartbeat was updated")
-
 					if err := worker.database.UpdateMetricsHeartbeat(); err != nil {
-						worker.logger.Info().
+						worker.logger.Error().
 							Error(err).
-							Msg("Save state failed")
+							Msg("Update metrics heartbeat failed")
 					} else {
+						worker.logger.Debug().
+							Int64("from", count).
+							Int64("to", newCount).
+							Msg("Heartbeat was updated")
+
 						count = newCount
 					}
 				}
 			}
 		}
 	})
+
 	worker.logger.Info().Msg("Moira Filter Heartbeat started")
 }
 
diff --git a/filter/metrics_parser.go b/filter/metrics_parser.go
index 12b028de3..2a0fa5922 100644
--- a/filter/metrics_parser.go
+++ b/filter/metrics_parser.go
@@ -31,14 +31,17 @@ func ParseMetric(input []byte) (*ParsedMetric, error) {
 	if !inputScanner.HasNext() {
 		return nil, fmt.Errorf("too few space-separated items: '%s'", input)
 	}
+
 	metricBytes = inputScanner.Next()
 	if !inputScanner.HasNext() {
 		return nil, fmt.Errorf("too few space-separated items: '%s'", input)
 	}
+
 	valueBytes = inputScanner.Next()
 	if !inputScanner.HasNext() {
 		return nil, fmt.Errorf("too few space-separated items: '%s'", input)
 	}
+
 	timestampBytes = inputScanner.Next()
 	if inputScanner.HasNext() {
 		return nil, fmt.Errorf("too many space-separated items: '%s'", input)
@@ -66,9 +69,11 @@ func ParseMetric(input []byte) (*ParsedMetric, error) {
 		value,
 		int64(timestamp),
 	}
+
 	if timestamp == -1 {
 		parsedMetric.Timestamp = time.Now().Unix()
 	}
+
 	return parsedMetric, nil
 }
 
@@ -78,6 +83,7 @@ func restoreMetricStringByNameAndLabels(name string, labels map[string]string) s
 	for key := range labels {
 		keys = append(keys, key)
 	}
+
 	sort.Strings(keys)
 
 	builder.WriteString(name)
@@ -104,10 +110,12 @@ func parseNameAndLabels(metricBytes []byte) (string, map[string]string, error) {
 	if !metricBytesScanner.HasNext() {
 		return "", nil, fmt.Errorf("too few colon-separated items: '%s'", metricBytes)
 	}
+
 	nameBytes := metricBytesScanner.Next()
 	if len(nameBytes) == 0 {
 		return "", nil, fmt.Errorf("empty metric name: '%s'", metricBytes)
 	}
+
 	name := moira.UnsafeBytesToString(nameBytes)
 	labels := make(map[string]string)
 	for metricBytesScanner.HasNext() {
@@ -118,10 +126,12 @@ func parseNameAndLabels(metricBytes []byte) (string, map[string]string, error) {
 		if !labelBytesScanner.HasNext() {
 			return "", nil, fmt.Errorf("too few equal-separated items: '%s'", labelBytes)
 		}
+
 		labelNameBytes = labelBytesScanner.Next()
 		if !labelBytesScanner.HasNext() {
 			return "", nil, fmt.Errorf("too few equal-separated items: '%s'", labelBytes)
 		}
+
 		labelValueBytes = labelBytesScanner.Next()
 		for labelBytesScanner.HasNext() {
 			var labelString strings.Builder
@@ -129,13 +139,16 @@ func parseNameAndLabels(metricBytes []byte) (string, map[string]string, error) {
 			labelString.Write(labelBytesScanner.Next())
 			labelValueBytes = append(labelValueBytes, labelString.String()...)
 		}
+
 		if len(labelNameBytes) == 0 {
 			return "", nil, fmt.Errorf("empty label name: '%s'", labelBytes)
 		}
+
 		labelName := moira.UnsafeBytesToString(labelNameBytes)
 		labelValue := moira.UnsafeBytesToString(labelValueBytes)
 		labels[labelName] = labelValue
 	}
+
 	return name, labels, nil
 }
 
diff --git a/filter/patterns_storage.go b/filter/patterns_storage.go
index a9e819750..10b8437af 100644
--- a/filter/patterns_storage.go
+++ b/filter/patterns_storage.go
@@ -74,6 +74,7 @@ func (storage *PatternStorage) ProcessIncomingMetric(lineBytes []byte, maxTTL ti
 		storage.logger.Info().
 			Error(err).
 			Msg("Cannot parse input")
+
 		return nil
 	}
 
@@ -82,6 +83,7 @@ func (storage *PatternStorage) ProcessIncomingMetric(lineBytes []byte, maxTTL ti
 			String(moira.LogFieldNameMetricName, parsedMetric.Name).
 			String(moira.LogFieldNameMetricTimestamp, fmt.Sprint(parsedMetric.Timestamp)).
 			Msg("Metric is too old")
+
 		return nil
 	}
 
@@ -92,6 +94,7 @@ func (storage *PatternStorage) ProcessIncomingMetric(lineBytes []byte, maxTTL ti
 	if count%10 == 0 {
 		storage.metrics.MatchingTimer.UpdateSince(matchingStart)
 	}
+
 	if len(matchedPatterns) > 0 {
 		storage.metrics.MatchingMetricsReceived.Inc()
 		return &moira.MatchedMetric{
diff --git a/filter/prefix_tree.go b/filter/prefix_tree.go
index dc5245291..7a4ee7eab 100644
--- a/filter/prefix_tree.go
+++ b/filter/prefix_tree.go
@@ -41,6 +41,7 @@ func (source *PrefixTree) AddWithPayload(pattern string, payloadKey string, payl
 			Msg("Pattern is ignored because it contains an empty part")
 		return
 	}
+
 	for i, part := range parts {
 		found := false
 		for _, child := range currentNode.Children {
@@ -50,6 +51,7 @@ func (source *PrefixTree) AddWithPayload(pattern string, payloadKey string, payl
 				break
 			}
 		}
+
 		if !found {
 			newNode := &PatternNode{Part: part}
 
@@ -76,9 +78,11 @@ func (source *PrefixTree) AddWithPayload(pattern string, payloadKey string, payl
 					newNode.InnerParts = []string{part}
 				}
 			}
+
 			currentNode.Children = append(currentNode.Children, newNode)
 			currentNode = newNode
 		}
+
 		if i == len(parts)-1 {
 			currentNode.Terminal = true
 			if payloadValue != nil {
@@ -121,6 +125,7 @@ func (source *PrefixTree) MatchWithValue(metric string) map[string]MatchingHandl
 			if node.Payload == nil {
 				matched[node.Prefix] = nil
 			}
+
 			for pattern, matchingHandler := range node.Payload {
 				matched[pattern] = matchingHandler
 			}
@@ -158,6 +163,7 @@ func (source *PrefixTree) findNodes(metric string) ([]*PatternNode, int) {
 	if found == 0 {
 		return nil, 0
 	}
+
 	return currentLevel, found
 }
 
@@ -186,6 +192,7 @@ func findPart(part string, currentLevel []*PatternNode) ([]*PatternNode, int) {
 			}
 		}
 	}
+
 	return nextLevel, len(nextLevel)
 }
 
@@ -194,6 +201,7 @@ func split2(s, sep string) (string, string) {
 	if len(splitResult) < 2 { //nolint
 		return splitResult[0], ""
 	}
+
 	return splitResult[0], splitResult[1]
 }
 
@@ -203,5 +211,6 @@ func hasEmptyParts(parts []string) bool {
 			return true
 		}
 	}
+
 	return false
 }
diff --git a/filter/series_by_tag.go b/filter/series_by_tag.go
index 169d6b907..03bfa1395 100644
--- a/filter/series_by_tag.go
+++ b/filter/series_by_tag.go
@@ -62,6 +62,7 @@ func transformWildcardToRegexpInSeriesByTag(input string) (string, bool) {
 		for i := range slc {
 			slc[i] = strings.TrimSpace(slc[i])
 		}
+
 		regularExpression = strings.Join(slc, "|")
 		result = result[:matchedWildcardIndexes[0]] + regularExpression + result[matchedWildcardIndexes[1]:]
 		isTransformed = true
@@ -70,6 +71,7 @@ func transformWildcardToRegexpInSeriesByTag(input string) (string, bool) {
 	if !isTransformed {
 		return input, false
 	}
+
 	return "^" + result + "$", true
 }
 
@@ -152,6 +154,7 @@ func CreateMatchingHandlerForPattern(tagSpecs []TagSpec, compatibility *Compatib
 				return false
 			}
 		}
+
 		return true
 	}
 
@@ -205,9 +208,11 @@ func createMatchingHandlerForOneTag(spec TagSpec, compatibility *Compatibility)
 		if spec.Name == "name" {
 			return matchingHandlerCondition(metric)
 		}
+
 		if value, found := labels[spec.Name]; found {
 			return matchingHandlerCondition(value)
 		}
+
 		return allowMatchEmpty && matchEmpty
 	}, nil
 }
diff --git a/filter/series_by_tag_pattern_index.go b/filter/series_by_tag_pattern_index.go
index 19186a442..7505cc5ef 100644
--- a/filter/series_by_tag_pattern_index.go
+++ b/filter/series_by_tag_pattern_index.go
@@ -26,7 +26,7 @@ func NewSeriesByTagPatternIndex(
 	for pattern, tagSpecs := range tagSpecsByPattern {
 		nameTagValue, matchingHandler, err := CreateMatchingHandlerForPattern(tagSpecs, &compatibility)
 		if err != nil {
-			logger.Info().
+			logger.Error().
 				Error(err).
 				String("pattern", pattern).
 				Msg("Failed to create MatchingHandler for pattern")