diff --git a/commands/configtest.go b/commands/configtest.go
index dfe94b2a..eb0b41ea 100644
--- a/commands/configtest.go
+++ b/commands/configtest.go
@@ -20,8 +20,10 @@ package commands
 import (
 	"context"
 	"flag"
+	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
 
 	"github.com/google/subcommands"
 
@@ -98,7 +100,7 @@ func (p *ConfigtestCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interfa
 	util.Log = util.NewCustomLogger(c.ServerInfo{})
 
 	if err := mkdirDotVuls(); err != nil {
-		util.Log.Errorf("Failed to create .vuls: %s", err)
+		util.Log.Errorf("Failed to create .vuls. err: %+v", err)
 		return subcommands.ExitUsageError
 	}
 
@@ -114,9 +116,12 @@ func (p *ConfigtestCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interfa
 
 	err = c.Load(p.configPath, keyPass)
 	if err != nil {
-		util.Log.Errorf("Error loading %s, %s", p.configPath, err)
-		util.Log.Errorf("If you update Vuls and get this error, there may be incompatible changes in config.toml")
-		util.Log.Errorf("Please check README: https://github.com/future-architect/vuls#configuration")
+		msg := []string{
+			fmt.Sprintf("Error loading %s", p.configPath),
+			"If you update Vuls and get this error, there may be incompatible changes in config.toml",
+			"Please check README: https://github.com/future-architect/vuls#configuration",
+		}
+		util.Log.Errorf("%s\n%+v", strings.Join(msg, "\n"), err)
 		return subcommands.ExitUsageError
 	}
 
@@ -151,13 +156,13 @@ func (p *ConfigtestCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interfa
 
 	util.Log.Info("Detecting Server/Container OS... ")
 	if err := scan.InitServers(p.timeoutSec); err != nil {
-		util.Log.Errorf("Failed to init servers: %s", err)
+		util.Log.Errorf("Failed to init servers. err: %+v", err)
 		return subcommands.ExitFailure
 	}
 
 	util.Log.Info("Checking Scan Modes...")
 	if err := scan.CheckScanModes(); err != nil {
-		util.Log.Errorf("Fix config.toml: %s", err)
+		util.Log.Errorf("Fix config.toml. err: %+v", err)
 		return subcommands.ExitFailure
 	}
 
diff --git a/commands/report.go b/commands/report.go
index 1b3691c5..9e1e61e7 100644
--- a/commands/report.go
+++ b/commands/report.go
@@ -209,7 +209,7 @@ func (p *ReportCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}
 	cvelog.SetLogger(c.Conf.LogDir, false, c.Conf.Debug, false)
 
 	if err := c.Load(p.configPath, ""); err != nil {
-		util.Log.Errorf("Error loading %s, %s", p.configPath, err)
+		util.Log.Errorf("Error loading %s, %+v", p.configPath, err)
 		return subcommands.ExitUsageError
 	}
 
@@ -227,7 +227,7 @@ func (p *ReportCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}
 		dir, err = report.JSONDir(f.Args())
 	}
 	if err != nil {
-		util.Log.Errorf("Failed to read from JSON: %s", err)
+		util.Log.Errorf("Failed to read from JSON: %+v", err)
 		return subcommands.ExitFailure
 	}
 
@@ -276,7 +276,7 @@ func (p *ReportCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}
 
 	if c.Conf.ToS3 {
 		if err := report.CheckIfBucketExists(); err != nil {
-			util.Log.Errorf("Check if there is a bucket beforehand: %s, err: %s",
+			util.Log.Errorf("Check if there is a bucket beforehand: %s, err: %+v",
 				c.Conf.AWS.S3Bucket, err)
 			return subcommands.ExitUsageError
 		}
@@ -297,7 +297,7 @@ func (p *ReportCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}
 			return subcommands.ExitUsageError
 		}
 		if err := report.CheckIfAzureContainerExists(); err != nil {
-			util.Log.Errorf("Check if there is a container beforehand: %s, err: %s",
+			util.Log.Errorf("Check if there is a container beforehand: %s, err: %+v",
 				c.Conf.Azure.ContainerName, err)
 			return subcommands.ExitUsageError
 		}
@@ -348,7 +348,7 @@ func (p *ReportCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}
 	if c.Conf.UUID {
 		// Ensure UUIDs of scan target servers in config.toml
 		if err := report.EnsureUUIDs(p.configPath, res); err != nil {
-			util.Log.Errorf("Failed to ensure UUIDs: %s", err)
+			util.Log.Errorf("Failed to ensure UUIDs. err: %+v", err)
 			return subcommands.ExitFailure
 		}
 	}
@@ -361,7 +361,7 @@ func (p *ReportCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}
 
 		if c.Conf.CveDict.URL != "" {
 			if err := report.CveClient.CheckHealth(); err != nil {
-				util.Log.Errorf("CVE HTTP server is not running. err: %s", err)
+				util.Log.Errorf("CVE HTTP server is not running. err: %+v", err)
 				util.Log.Errorf("Run go-cve-dictionary as server mode before reporting or run with `-cvedb-type=sqlite3 -cvedb-sqlite3-path` option instead of -cvedb-url")
 				return subcommands.ExitFailure
 			}
@@ -370,7 +370,7 @@ func (p *ReportCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}
 		if c.Conf.OvalDict.URL != "" {
 			err := oval.Base{}.CheckHTTPHealth()
 			if err != nil {
-				util.Log.Errorf("OVAL HTTP server is not running. err: %s", err)
+				util.Log.Errorf("OVAL HTTP server is not running. err: %+v", err)
 				util.Log.Errorf("Run goval-dictionary as server mode before reporting or run with `-ovaldb-type=sqlite3 -ovaldb-sqlite3-path` option instead of -ovaldb-url")
 				return subcommands.ExitFailure
 			}
@@ -380,7 +380,7 @@ func (p *ReportCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}
 			util.Log.Infof("gost: %s", c.Conf.Gost.URL)
 			err := gost.Base{}.CheckHTTPHealth()
 			if err != nil {
-				util.Log.Errorf("gost HTTP server is not running. err: %s", err)
+				util.Log.Errorf("gost HTTP server is not running. err: %+v", err)
 				util.Log.Errorf("Run gost as server mode before reporting or run with `-gostdb-type=sqlite3 -gostdb-sqlite3-path` option instead of -gostdb-url")
 				return subcommands.ExitFailure
 			}
@@ -389,7 +389,7 @@ func (p *ReportCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}
 		if c.Conf.Exploit.URL != "" {
 			err := exploit.CheckHTTPHealth()
 			if err != nil {
-				util.Log.Errorf("exploit HTTP server is not running. err: %s", err)
+				util.Log.Errorf("exploit HTTP server is not running. err: %+v", err)
 				util.Log.Errorf("Run go-exploitdb as server mode before reporting")
 				return subcommands.ExitFailure
 			}
@@ -402,24 +402,24 @@ func (p *ReportCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}
 			DebugSQL:    c.Conf.DebugSQL,
 		})
 		if locked {
-			util.Log.Errorf("SQLite3 is locked. Close other DB connections and try again: %s", err)
+			util.Log.Errorf("SQLite3 is locked. Close other DB connections and try again. err: %+v", err)
 			return subcommands.ExitFailure
 		}
 		if err != nil {
-			util.Log.Errorf("Failed to init DB Clients: %s", err)
+			util.Log.Errorf("Failed to init DB Clients. err: %+v", err)
 			return subcommands.ExitFailure
 		}
 		defer dbclient.CloseDB()
 
 		if res, err = report.FillCveInfos(*dbclient, res, dir); err != nil {
-			util.Log.Error(err)
+			util.Log.Errorf("%+v", err)
 			return subcommands.ExitFailure
 		}
 	}
 
 	for _, w := range reports {
 		if err := w.Write(res...); err != nil {
-			util.Log.Errorf("Failed to report: %s", err)
+			util.Log.Errorf("Failed to report. err: %+v", err)
 			return subcommands.ExitFailure
 		}
 	}
diff --git a/commands/scan.go b/commands/scan.go
index b037a555..3a6ded7b 100644
--- a/commands/scan.go
+++ b/commands/scan.go
@@ -126,7 +126,7 @@ func (p *ScanCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{})
 	util.Log = util.NewCustomLogger(c.ServerInfo{})
 
 	if err := mkdirDotVuls(); err != nil {
-		util.Log.Errorf("Failed to create .vuls: %s", err)
+		util.Log.Errorf("Failed to create .vuls. err: %+v", err)
 		return subcommands.ExitUsageError
 	}
 
@@ -142,9 +142,12 @@ func (p *ScanCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{})
 
 	err = c.Load(p.configPath, keyPass)
 	if err != nil {
-		util.Log.Errorf("Error loading %s, %s", p.configPath, err)
-		util.Log.Errorf("If you update Vuls and get this error, there may be incompatible changes in config.toml")
-		util.Log.Errorf("Please check README: https://github.com/future-architect/vuls#configuration")
+		msg := []string{
+			fmt.Sprintf("Error loading %s", p.configPath),
+			"If you update Vuls and get this error, there may be incompatible changes in config.toml",
+			"Please check README: https://github.com/future-architect/vuls#configuration",
+		}
+		util.Log.Errorf("%s\n%+v", strings.Join(msg, "\n"), err)
 		return subcommands.ExitUsageError
 	}
 
@@ -157,7 +160,7 @@ func (p *ScanCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{})
 	} else if c.Conf.Pipe {
 		bytes, err := ioutil.ReadAll(os.Stdin)
 		if err != nil {
-			util.Log.Errorf("Failed to read stdin: %s", err)
+			util.Log.Errorf("Failed to read stdin. err: %+v", err)
 			return subcommands.ExitFailure
 		}
 		fields := strings.Fields(string(bytes))
@@ -193,13 +196,13 @@ func (p *ScanCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{})
 
 	util.Log.Info("Detecting Server/Container OS... ")
 	if err := scan.InitServers(p.timeoutSec); err != nil {
-		util.Log.Errorf("Failed to init servers: %s", err)
+		util.Log.Errorf("Failed to init servers: %+v", err)
 		return subcommands.ExitFailure
 	}
 
 	util.Log.Info("Checking Scan Modes... ")
 	if err := scan.CheckScanModes(); err != nil {
-		util.Log.Errorf("Fix config.toml: %s", err)
+		util.Log.Errorf("Fix config.toml. err: %+v", err)
 		return subcommands.ExitFailure
 	}
 
@@ -208,7 +211,7 @@ func (p *ScanCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{})
 
 	util.Log.Info("Scanning vulnerabilities... ")
 	if err := scan.Scan(p.scanTimeoutSec); err != nil {
-		util.Log.Errorf("Failed to scan. err: %s", err)
+		util.Log.Errorf("Failed to scan. err: %+v", err)
 		return subcommands.ExitFailure
 	}
 	fmt.Printf("\n\n\n")
diff --git a/commands/server.go b/commands/server.go
index 98dd46b3..930e67a3 100644
--- a/commands/server.go
+++ b/commands/server.go
@@ -152,7 +152,7 @@ func (p *ServerCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}
 	cvelog.SetLogger(c.Conf.LogDir, false, c.Conf.Debug, false)
 
 	if err := c.Load(p.configPath, ""); err != nil {
-		util.Log.Errorf("Error loading %s, %s", p.configPath, err)
+		util.Log.Errorf("Error loading %s. err: %+v", p.configPath, err)
 		return subcommands.ExitUsageError
 	}
 
@@ -173,7 +173,7 @@ func (p *ServerCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}
 
 	if c.Conf.CveDict.URL != "" {
 		if err := report.CveClient.CheckHealth(); err != nil {
-			util.Log.Errorf("CVE HTTP server is not running. err: %s", err)
+			util.Log.Errorf("CVE HTTP server is not running. err: %+v", err)
 			util.Log.Errorf("Run go-cve-dictionary as server mode before reporting or run with `-cvedb-type=sqlite3 -cvedb-sqlite3-path` option instead of -cvedb-url")
 			return subcommands.ExitFailure
 		}
@@ -192,7 +192,7 @@ func (p *ServerCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}
 		util.Log.Infof("gost: %s", c.Conf.Gost.URL)
 		err := gost.Base{}.CheckHTTPHealth()
 		if err != nil {
-			util.Log.Errorf("gost HTTP server is not running. err: %s", err)
+			util.Log.Errorf("gost HTTP server is not running. err: %+v", err)
 			util.Log.Errorf("Run gost as server mode before reporting or run with `-gostdb-type=sqlite3 -gostdb-sqlite3-path` option instead of -gostdb-url")
 			return subcommands.ExitFailure
 		}
@@ -201,7 +201,7 @@ func (p *ServerCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}
 	if c.Conf.Exploit.URL != "" {
 		err := exploit.CheckHTTPHealth()
 		if err != nil {
-			util.Log.Errorf("exploit HTTP server is not running. err: %s", err)
+			util.Log.Errorf("exploit HTTP server is not running. err: %+v", err)
 			util.Log.Errorf("Run go-exploitdb as server mode before reporting")
 			return subcommands.ExitFailure
 		}
@@ -215,12 +215,12 @@ func (p *ServerCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}
 		DebugSQL:    c.Conf.DebugSQL,
 	})
 	if locked {
-		util.Log.Errorf("SQLite3 is locked. Close other DB connections and try again: %s", err)
+		util.Log.Errorf("SQLite3 is locked. Close other DB connections and try again: %+v", err)
 		return subcommands.ExitFailure
 	}
 
 	if err != nil {
-		util.Log.Errorf("Failed to init DB Clients: %s", err)
+		util.Log.Errorf("Failed to init DB Clients. err: %+v", err)
 		return subcommands.ExitFailure
 	}
 
@@ -232,7 +232,7 @@ func (p *ServerCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}
 	})
 	util.Log.Infof("Listening on %s", p.listen)
 	if err := http.ListenAndServe(p.listen, nil); err != nil {
-		util.Log.Errorf("Failed to start server: %s", err)
+		util.Log.Errorf("Failed to start server. err: %+v", err)
 		return subcommands.ExitFailure
 	}
 	return subcommands.ExitSuccess
diff --git a/commands/tui.go b/commands/tui.go
index dd99a1e3..fe3936de 100644
--- a/commands/tui.go
+++ b/commands/tui.go
@@ -149,7 +149,7 @@ func (p *TuiCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}) s
 	cvelog.SetLogger(c.Conf.LogDir, false, c.Conf.Debug, false)
 
 	if err := c.Load(p.configPath, ""); err != nil {
-		util.Log.Errorf("Error loading %s, %s", p.configPath, err)
+		util.Log.Errorf("Error loading %s, err: %+v", p.configPath, err)
 		return subcommands.ExitUsageError
 	}
 
@@ -166,7 +166,7 @@ func (p *TuiCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}) s
 		dir, err = report.JSONDir(f.Args())
 	}
 	if err != nil {
-		util.Log.Errorf("Failed to read from JSON: %s", err)
+		util.Log.Errorf("Failed to read from JSON. err: %+v", err)
 		return subcommands.ExitFailure
 	}
 
@@ -189,7 +189,7 @@ func (p *TuiCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}) s
 
 	if c.Conf.CveDict.URL != "" {
 		if err := report.CveClient.CheckHealth(); err != nil {
-			util.Log.Errorf("CVE HTTP server is not running. err: %s", err)
+			util.Log.Errorf("CVE HTTP server is not running. err: %+v", err)
 			util.Log.Errorf("Run go-cve-dictionary as server mode before reporting or run with `-cvedb-type=sqlite3 -cvedb-sqlite3-path` option instead of -cvedb-url")
 			return subcommands.ExitFailure
 		}
@@ -198,7 +198,7 @@ func (p *TuiCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}) s
 	if c.Conf.OvalDict.URL != "" {
 		err := oval.Base{}.CheckHTTPHealth()
 		if err != nil {
-			util.Log.Errorf("OVAL HTTP server is not running. err: %s", err)
+			util.Log.Errorf("OVAL HTTP server is not running. err: %+v", err)
 			util.Log.Errorf("Run goval-dictionary as server mode before reporting or run with `-ovaldb-type=sqlite3 -ovaldb-sqlite3-path` option instead of -ovaldb-url")
 			return subcommands.ExitFailure
 		}
@@ -208,7 +208,7 @@ func (p *TuiCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}) s
 		util.Log.Infof("gost: %s", c.Conf.Gost.URL)
 		err := gost.Base{}.CheckHTTPHealth()
 		if err != nil {
-			util.Log.Errorf("gost HTTP server is not running. err: %s", err)
+			util.Log.Errorf("gost HTTP server is not running. err: %+v", err)
 			util.Log.Errorf("Run gost as server mode before reporting or run with `-gostdb-type=sqlite3 -gostdb-sqlite3-path` option instead of -gostdb-url")
 			return subcommands.ExitFailure
 		}
@@ -217,7 +217,7 @@ func (p *TuiCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}) s
 	if c.Conf.Exploit.URL != "" {
 		err := exploit.CheckHTTPHealth()
 		if err != nil {
-			util.Log.Errorf("exploit HTTP server is not running. err: %s", err)
+			util.Log.Errorf("exploit HTTP server is not running. err: %+v", err)
 			util.Log.Errorf("Run go-exploitdb as server mode before reporting")
 			return subcommands.ExitFailure
 		}
@@ -230,12 +230,12 @@ func (p *TuiCmd) Execute(_ context.Context, f *flag.FlagSet, _ ...interface{}) s
 		DebugSQL:    c.Conf.DebugSQL,
 	})
 	if locked {
-		util.Log.Errorf("SQLite3 is locked. Close other DB connections and try again: %s", err)
+		util.Log.Errorf("SQLite3 is locked. Close other DB connections and try again: %+v", err)
 		return subcommands.ExitFailure
 	}
 
 	if err != nil {
-		util.Log.Errorf("Failed to init DB Clients: %s", err)
+		util.Log.Errorf("Failed to init DB Clients. err: %+v", err)
 		return subcommands.ExitFailure
 	}
 
diff --git a/github/github.go b/github/github.go
index a4c1ff2b..dee5bd9b 100644
--- a/github/github.go
+++ b/github/github.go
@@ -30,6 +30,7 @@ import (
 	"github.com/future-architect/vuls/util"
 	"github.com/k0kubun/pp"
 	"golang.org/x/oauth2"
+	"golang.org/x/xerrors"
 )
 
 // FillGitHubSecurityAlerts access to owner/repo on GitHub and fetch scurity alerts of the repository via GitHub API v4 GraphQL and then set to the given ScanResult.
@@ -73,6 +74,9 @@ func FillGitHubSecurityAlerts(r *models.ScanResult, owner, repo, token string) (
 		}
 
 		util.Log.Debugf("%s", pp.Sprint(alerts))
+		if alerts.Data.Repository.URL == "" {
+			return 0, xerrors.Errorf("Failed to access to GitHub API. Response: %#v", alerts)
+		}
 
 		for _, v := range alerts.Data.Repository.VulnerabilityAlerts.Edges {
 			if config.Conf.IgnoreGitHubDismissed && v.Node.DismissReason != "" {
diff --git a/models/scanresults.go b/models/scanresults.go
index f6366d11..9e93a868 100644
--- a/models/scanresults.go
+++ b/models/scanresults.go
@@ -222,7 +222,7 @@ func (r ScanResult) FilterIgnorePkgs() ScanResult {
 	for _, pkgRegexp := range ignorePkgsRegexps {
 		re, err := regexp.Compile(pkgRegexp)
 		if err != nil {
-			util.Log.Errorf("Faild to parse %s, %s", pkgRegexp, err)
+			util.Log.Errorf("Faild to parse %s. err: %+v", pkgRegexp, err)
 			continue
 		} else {
 			regexps = append(regexps, re)
diff --git a/report/db_client.go b/report/db_client.go
index fbf4d45b..c5a54b53 100644
--- a/report/db_client.go
+++ b/report/db_client.go
@@ -139,7 +139,7 @@ func NewGostDB(cnf DBClientConf) (driver gostdb.DB, locked bool, err error) {
 	util.Log.Debugf("Open gost db (%s): %s", cnf.GostCnf.Type, path)
 	if driver, locked, err = gostdb.NewDB(cnf.GostCnf.Type, path, cnf.DebugSQL); err != nil {
 		if locked {
-			util.Log.Errorf("gostDB is locked: %s", err)
+			util.Log.Errorf("gostDB is locked. err: %+v", err)
 			return nil, true, err
 		}
 		return nil, false, err
@@ -165,7 +165,7 @@ func NewExploitDB(cnf DBClientConf) (driver exploitdb.DB, locked bool, err error
 	util.Log.Debugf("Open exploit db (%s): %s", cnf.ExploitCnf.Type, path)
 	if driver, locked, err = exploitdb.NewDB(cnf.ExploitCnf.Type, path, cnf.DebugSQL); err != nil {
 		if locked {
-			util.Log.Errorf("exploitDB is locked: %s", err)
+			util.Log.Errorf("exploitDB is locked. err: %+v", err)
 			return nil, true, err
 		}
 		return nil, false, err
@@ -177,12 +177,12 @@ func NewExploitDB(cnf DBClientConf) (driver exploitdb.DB, locked bool, err error
 func (d DBClient) CloseDB() {
 	if d.CveDB != nil {
 		if err := d.CveDB.CloseDB(); err != nil {
-			util.Log.Errorf("Failed to close DB: %s", err)
+			util.Log.Errorf("Failed to close DB. err: %+v", err)
 		}
 	}
 	if d.OvalDB != nil {
 		if err := d.OvalDB.CloseDB(); err != nil {
-			util.Log.Errorf("Failed to close DB: %s", err)
+			util.Log.Errorf("Failed to close DB. err: %+v", err)
 		}
 	}
 }
diff --git a/report/report.go b/report/report.go
index c131c0d4..ffea24f8 100644
--- a/report/report.go
+++ b/report/report.go
@@ -186,7 +186,7 @@ func FillCveInfo(dbclient DBClient, r *models.ScanResult, cpeURIs []string, inte
 	ints := &integrationResults{}
 	for _, o := range integrations {
 		if err = o.apply(r, ints); err != nil {
-			return err
+			return xerrors.Errorf("Failed to fill with integration: %w", err)
 		}
 	}
 	util.Log.Infof("%s: %d CVEs are detected with GitHub Security Alerts", r.FormatServerName(), ints.GithubAlertsCveCounts)
diff --git a/report/saas.go b/report/saas.go
index 50c746ca..630461e4 100644
--- a/report/saas.go
+++ b/report/saas.go
@@ -67,7 +67,7 @@ func (w SaasWriter) Write(rs ...models.ScanResult) (err error) {
 
 	ipv4s, ipv6s, err := util.IP()
 	if err != nil {
-		util.Log.Errorf("Failed to fetch scannedIPs: %s", err)
+		util.Log.Errorf("Failed to fetch scannedIPs. err: %+v", err)
 	}
 	hostname, _ := os.Hostname()
 
diff --git a/report/tui.go b/report/tui.go
index 0e3b4105..4cda1ccd 100644
--- a/report/tui.go
+++ b/report/tui.go
@@ -56,14 +56,14 @@ func RunTui(results models.ScanResults) subcommands.ExitStatus {
 
 	g, err := gocui.NewGui(gocui.OutputNormal)
 	if err != nil {
-		util.Log.Errorf("%s", err)
+		util.Log.Errorf("%+v", err)
 		return subcommands.ExitFailure
 	}
 	defer g.Close()
 
 	g.SetManagerFunc(layout)
 	if err := keybindings(g); err != nil {
-		util.Log.Errorf("%s", err)
+		util.Log.Errorf("%+v", err)
 		return subcommands.ExitFailure
 	}
 	g.SelBgColor = gocui.ColorGreen
@@ -72,7 +72,7 @@ func RunTui(results models.ScanResults) subcommands.ExitStatus {
 
 	if err := g.MainLoop(); err != nil {
 		g.Close()
-		util.Log.Errorf("%s", err)
+		util.Log.Errorf("%+v", err)
 		os.Exit(1)
 	}
 	return subcommands.ExitSuccess
diff --git a/report/util.go b/report/util.go
index 7b6d9591..bcccbedd 100644
--- a/report/util.go
+++ b/report/util.go
@@ -399,7 +399,7 @@ func loadPrevious(currs models.ScanResults) (prevs models.ScanResults, err error
 			path := filepath.Join(dir, filename)
 			r, err := loadOneServerScanResult(path)
 			if err != nil {
-				util.Log.Errorf("%s", err)
+				util.Log.Errorf("%+v", err)
 				continue
 			}
 			if r.Family == result.Family && r.Release == result.Release {
diff --git a/scan/executil.go b/scan/executil.go
index ad7811fd..8c7c329e 100644
--- a/scan/executil.go
+++ b/scan/executil.go
@@ -125,11 +125,7 @@ func parallelExec(fn func(osTypeInterface) error, timeoutSec ...int) {
 			if len(s.getErrs()) == 0 {
 				successes = append(successes, s)
 			} else {
-				fmtstr := "Error on %s, err: %s"
-				if conf.Conf.Debug {
-					fmtstr = "Error: %s, err: %+v"
-				}
-				util.Log.Errorf(fmtstr,
+				util.Log.Errorf("Error on %s, err: %+v",
 					s.getServerInfo().GetServerName(), s.getErrs())
 				errServers = append(errServers, s)
 			}
@@ -150,10 +146,10 @@ func parallelExec(fn func(osTypeInterface) error, timeoutSec ...int) {
 				}
 			}
 			if !found {
-				msg := fmt.Sprintf("Timed out: %s",
+				err := xerrors.Errorf("Timed out: %s",
 					s.getServerInfo().GetServerName())
-				util.Log.Errorf(msg)
-				s.setErrs([]error{xerrors.New(msg)})
+				util.Log.Errorf("%+v", err)
+				s.setErrs([]error{err})
 				errServers = append(errServers, s)
 			}
 		}
diff --git a/scan/serverapi.go b/scan/serverapi.go
index cacf193c..64c2d5c0 100644
--- a/scan/serverapi.go
+++ b/scan/serverapi.go
@@ -215,7 +215,7 @@ func detectServerOSes(timeoutSec int) (servers, errServers []osTypeInterface) {
 		case res := <-osTypeChan:
 			if 0 < len(res.getErrs()) {
 				errServers = append(errServers, res)
-				util.Log.Errorf("(%d/%d) Failed: %s, err: %s",
+				util.Log.Errorf("(%d/%d) Failed: %s, err: %+v",
 					i+1, len(config.Conf.Servers),
 					res.getServerInfo().ServerName,
 					res.getErrs())
@@ -279,7 +279,7 @@ func detectContainerOSes(timeoutSec int) (actives, inactives []osTypeInterface)
 				sinfo := osi.getServerInfo()
 				if 0 < len(osi.getErrs()) {
 					inactives = append(inactives, osi)
-					util.Log.Errorf("Failed: %s err: %s", sinfo.ServerName, osi.getErrs())
+					util.Log.Errorf("Failed: %s err: %+v", sinfo.ServerName, osi.getErrs())
 					continue
 				}
 				actives = append(actives, osi)
@@ -600,7 +600,7 @@ func scanVulns(jsonDir string, scannedAt time.Time, timeoutSec int) error {
 	hostname, _ := os.Hostname()
 	ipv4s, ipv6s, err := util.IP()
 	if err != nil {
-		util.Log.Errorf("Failed to fetch scannedIPs: %s", err)
+		util.Log.Errorf("Failed to fetch scannedIPs. err: %+v", err)
 	}
 
 	for _, s := range append(servers, errServers...) {
diff --git a/server/server.go b/server/server.go
index 996156a2..06ff9641 100644
--- a/server/server.go
+++ b/server/server.go
@@ -87,7 +87,7 @@ func (h VulsHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		}
 		dir, err := scan.EnsureResultDir(scannedAt)
 		if err != nil {
-			util.Log.Errorf("Failed to ensure the result directory: %s", err)
+			util.Log.Errorf("Failed to ensure the result directory: %+v", err)
 			http.Error(w, err.Error(), http.StatusServiceUnavailable)
 			return
 		}
@@ -99,7 +99,7 @@ func (h VulsHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	for _, w := range reports {
 		if err := w.Write(result); err != nil {
-			util.Log.Errorf("Failed to report: %s", err)
+			util.Log.Errorf("Failed to report. err: %+v", err)
 			return
 		}
 	}