diff --git a/README.md b/README.md
index 5516776..fe07c1b 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ build/sicra -h
 
 Usage of build/sicra:
   -add-error
-        Add URL to sitemap, even if response error (default true)
+        Add URL to sitemap, even if response error (only for 5xx codes) (default true)
   -async
         Run async requests
   -delay int
diff --git a/main.go b/main.go
index 5e6dfa6..c19acdf 100644
--- a/main.go
+++ b/main.go
@@ -11,7 +11,7 @@ import (
 )
 
 func main() {
-	addError := flag.Bool("add-error", true, "Add URL to sitemap, even if response error")
+	addError := flag.Bool("add-error", true, "Add URL to sitemap, even if response error (only for 5xx codes)")
 	asyncScan := flag.Bool("async", false, "Run async requests")
 	delay := flag.Int64("delay", 0, "Delay between requests in Millisecond")
 	maxDepth := flag.Int("max-depth", 0, "MaxDepth limits the recursion depth of visited URLs.")
@@ -49,24 +49,38 @@ func main() {
 		*skipNoIndex,
 		*verbose)
 
-	err = sicra.GenerateSiteMap(*outFile, scrape.AddedURLs)
-	if err != nil {
-		log.Fatal(err)
+	p := filepath.Dir(*outFile)
+	// generate sitemap.xml
+	if len(scrape.AddedURLs) > 0 {
+		err = sicra.GenerateSiteMap(*outFile, scrape.AddedURLs)
+		if err != nil {
+			log.Fatal(err)
+		}
 	}
-
+	// generate noindex.txt
 	if *skipNoIndex {
-		p := filepath.Dir(*outFile)
-		err = sicra.GenerateNoIndex(p+"/noindex.txt", scrape.NoIndexURLs)
+		if len(scrape.NoIndexURLs) > 0 {
+			err = sicra.GenerateTxt(p+"/noindex.txt", scrape.NoIndexURLs)
+			if err != nil {
+				log.Fatal(err)
+			}
+		}
+	}
+	// generate errors.txt
+	if len(scrape.ErrorURLs) > 0 {
+		err = sicra.GenerateTxt(p+"/errors.txt", scrape.ErrorURLs)
 		if err != nil {
 			log.Fatal(err)
 		}
 	}
-
-	fmt.Print(
-		"Request URLs: ", scrape.AllVisitURLsCount, "\n",
-		"Added URLs ", scrape.AddedURLsCount, "\n",
-		"No Index URLs ", scrape.NoIndexURLsCount, "\n",
-		"Response URLs ", scrape.ResponseURLsCount, "\n",
-		"Error URLs ", scrape.ErrorURLsCount, "\n",
-	)
+	// print stats
+	if *verbose {
+		fmt.Print(
+			"Request URLs: ", scrape.AllVisitURLsCount, "\n",
+			"Added URLs ", scrape.AddedURLsCount, "\n",
+			"No Index URLs ", scrape.NoIndexURLsCount, "\n",
+			"Response URLs ", scrape.ResponseURLsCount, "\n",
+			"Error URLs ", scrape.ErrorURLsCount, "\n",
+		)
+	}
 }
diff --git a/sicra/crawler.go b/sicra/crawler.go
index c85d588..94cb3b0 100644
--- a/sicra/crawler.go
+++ b/sicra/crawler.go
@@ -1,9 +1,11 @@
 package sicra
 
 import (
+	"fmt"
 	"log"
 	"net/url"
 	"regexp"
+	"strconv"
 	"time"
 
 	"github.com/gocolly/colly"
@@ -13,9 +15,10 @@ type scrapeURL struct {
 	AddedURLs         []string
 	AddedURLsCount    int
 	AllVisitURLsCount int
+	ErrorURLs         []string
 	ErrorURLsCount    int
-	NoIndexURLsCount  int
 	NoIndexURLs       []string
+	NoIndexURLsCount  int
 	ResponseURLsCount int
 }
 
@@ -68,13 +71,19 @@ func Crawler(
 
 	c.OnError(func(er *colly.Response, err error) {
 		requestURL := urlEscape(er.Request.URL.String())
+		r := regexp.MustCompile("^5[0-9]{1,2}$")
+		statusCode := strconv.Itoa(er.StatusCode)
+		strErr := fmt.Sprint(err)
 		if verbose {
 			log.Println("Error:", err, requestURL)
 		}
 		if addError {
-			add(requestURL, verbose, scrapeURLs)
+			if r.MatchString(statusCode) {
+				add(requestURL, verbose, scrapeURLs)
+			}
 		}
 		scrapeURLs.ErrorURLsCount++
+		scrapeURLs.ErrorURLs = append(scrapeURLs.ErrorURLs, statusCode+" "+strErr+" "+requestURL)
 	})
 
 	c.OnResponse(func(re *colly.Response) {
diff --git a/sicra/sitemap.go b/sicra/sitemap.go
index 98d1109..a805629 100644
--- a/sicra/sitemap.go
+++ b/sicra/sitemap.go
@@ -24,7 +24,7 @@ func GenerateSiteMap(fileName string, urls []string) error {
 	for _, loc := range urls {
 		fh.WriteString("    " + "<url>\n")
 		fh.WriteString("      " + "<loc>" + loc + "</loc>\n")
-		fh.WriteString("      " + "<changefreq>" + currentTime + "</changefreq>\n")
+		fh.WriteString("      " + "<lastmod>" + currentTime + "</lastmod>\n")
 		fh.WriteString("      " + "<changefreq>hourly</changefreq>\n")
 		fh.WriteString("      " + "<priority>0.5</priority>\n")
 		fh.WriteString("    " + "</url>\n")
@@ -34,7 +34,8 @@ func GenerateSiteMap(fileName string, urls []string) error {
 	return nil
 }
 
-func GenerateNoIndex(fileName string, urls []string) error {
+// GenerateTxt generate txt file for error list url or skiped  noindex
+func GenerateTxt(fileName string, urls []string) error {
 	err := deleteFileIfExists(fileName)
 	if err != nil {
 		log.Fatal(err)
diff --git a/test/error.conf b/test/error.conf
new file mode 100644
index 0000000..9050bc7
--- /dev/null
+++ b/test/error.conf
@@ -0,0 +1,23 @@
+server {
+  listen 8080;
+  server_name _;
+
+  location /403 {
+    return 403;
+  }
+  location /404 {
+    return 404;
+  }
+    location /500 {
+    return 500;
+  }
+  location /502 {
+    return 502;
+  }
+  location /444 {
+    return 444;
+  }
+    location /555 {
+    return 555;
+  }
+}