diff --git a/models/errors/errors.go b/models/errors/errors.go
new file mode 100644
index 000000000..43ed63352
--- /dev/null
+++ b/models/errors/errors.go
@@ -0,0 +1,12 @@
+// Copyright 2017 The Gogs Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package errors
+
+import "errors"
+
+// New is a wrapper of real errors.New function.
+func New(text string) error {
+	return errors.New(text)
+}
diff --git a/models/errors/issue.go b/models/errors/issue.go
new file mode 100644
index 000000000..4ea898fb9
--- /dev/null
+++ b/models/errors/issue.go
@@ -0,0 +1,20 @@
+// Copyright 2017 The Gogs Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package errors
+
+import "fmt"
+
+type InvalidIssueReference struct {
+	Ref string
+}
+
+func IsInvalidIssueReference(err error) bool {
+	_, ok := err.(InvalidIssueReference)
+	return ok
+}
+
+func (err InvalidIssueReference) Error() string {
+	return fmt.Sprintf("invalid issue reference [ref: %s]", err.Ref)
+}
diff --git a/models/errors/login_source.go b/models/errors/login_source.go
new file mode 100644
index 000000000..db0cd1f9d
--- /dev/null
+++ b/models/errors/login_source.go
@@ -0,0 +1,33 @@
+// Copyright 2017 The Gogs Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package errors
+
+import "fmt"
+
+type LoginSourceNotActivated struct {
+	SourceID int64
+}
+
+func IsLoginSourceNotActivated(err error) bool {
+	_, ok := err.(LoginSourceNotActivated)
+	return ok
+}
+
+func (err LoginSourceNotActivated) Error() string {
+	return fmt.Sprintf("login source is not activated [source_id: %d]", err.SourceID)
+}
+
+type InvalidLoginSourceType struct {
+	Type interface{}
+}
+
+func IsInvalidLoginSourceType(err error) bool {
+	_, ok := err.(InvalidLoginSourceType)
+	return ok
+}
+
+func (err InvalidLoginSourceType) Error() string {
+	return fmt.Sprintf("invalid login source type [type: %v]", err.Type)
+}
diff --git a/models/errors/repo.go b/models/errors/repo.go
new file mode 100644
index 000000000..9abcaaa93
--- /dev/null
+++ b/models/errors/repo.go
@@ -0,0 +1,33 @@
+// Copyright 2017 The Gogs Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package errors
+
+import "fmt"
+
+type InvalidRepoReference struct {
+	Ref string
+}
+
+func IsInvalidRepoReference(err error) bool {
+	_, ok := err.(InvalidRepoReference)
+	return ok
+}
+
+func (err InvalidRepoReference) Error() string {
+	return fmt.Sprintf("invalid repository reference [ref: %s]", err.Ref)
+}
+
+type MirrorNotExist struct {
+	RepoID int64
+}
+
+func IsMirrorNotExist(err error) bool {
+	_, ok := err.(MirrorNotExist)
+	return ok
+}
+
+func (err MirrorNotExist) Error() string {
+	return fmt.Sprintf("mirror does not exist [repo_id: %d]", err.RepoID)
+}
diff --git a/models/errors/user.go b/models/errors/user.go
new file mode 100644
index 000000000..cda49e0ef
--- /dev/null
+++ b/models/errors/user.go
@@ -0,0 +1,31 @@
+// Copyright 2017 The Gogs Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package errors
+
+import "fmt"
+
+type EmptyName struct{}
+
+func IsEmptyName(err error) bool {
+	_, ok := err.(EmptyName)
+	return ok
+}
+
+func (err EmptyName) Error() string {
+	return "empty name"
+}
+
+type UserNotKeyOwner struct {
+	KeyID int64
+}
+
+func IsUserNotKeyOwner(err error) bool {
+	_, ok := err.(UserNotKeyOwner)
+	return ok
+}
+
+func (err UserNotKeyOwner) Error() string {
+	return fmt.Sprintf("user is not the owner of public key [key_id: %d]", err.KeyID)
+}
diff --git a/models/errors/user_mail.go b/models/errors/user_mail.go
new file mode 100644
index 000000000..fcdeb78c2
--- /dev/null
+++ b/models/errors/user_mail.go
@@ -0,0 +1,33 @@
+// Copyright 2017 The Gogs Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package errors
+
+import "fmt"
+
+type EmailNotFound struct {
+	Email string
+}
+
+func IsEmailNotFound(err error) bool {
+	_, ok := err.(EmailNotFound)
+	return ok
+}
+
+func (err EmailNotFound) Error() string {
+	return fmt.Sprintf("email is not found [email: %s]", err.Email)
+}
+
+type EmailNotVerified struct {
+	Email string
+}
+
+func IsEmailNotVerified(err error) bool {
+	_, ok := err.(EmailNotVerified)
+	return ok
+}
+
+func (err EmailNotVerified) Error() string {
+	return fmt.Sprintf("email has not been verified [email: %s]", err.Email)
+}
diff --git a/models/issue.go b/models/issue.go
index 8cf5add3c..8bc5914c6 100644
--- a/models/issue.go
+++ b/models/issue.go
@@ -5,7 +5,6 @@
 package models
 
 import (
-	"errors"
 	"fmt"
 	"strings"
 	"time"
@@ -16,6 +15,7 @@ import (
 
 	api "github.com/gogits/go-gogs-client"
 
+	"github.com/gogits/gogs/models/errors"
 	"github.com/gogits/gogs/modules/base"
 	"github.com/gogits/gogs/modules/setting"
 )
@@ -796,7 +796,7 @@ func NewIssue(repo *Repository, issue *Issue, labelIDs []int64, uuids []string)
 func GetIssueByRef(ref string) (*Issue, error) {
 	n := strings.IndexByte(ref, byte('#'))
 	if n == -1 {
-		return nil, ErrMissingIssueNumber
+		return nil, errors.InvalidIssueReference{ref}
 	}
 
 	index, err := com.StrTo(ref[n+1:]).Int64()
diff --git a/models/login_source.go b/models/login_source.go
index 8a30ad228..1191994dc 100644
--- a/models/login_source.go
+++ b/models/login_source.go
@@ -7,7 +7,6 @@ package models
 import (
 	"crypto/tls"
 	"encoding/json"
-	"errors"
 	"fmt"
 	"net/smtp"
 	"net/textproto"
@@ -20,6 +19,7 @@ import (
 	"github.com/go-xorm/xorm"
 	log "gopkg.in/clog.v1"
 
+	"github.com/gogits/gogs/models/errors"
 	"github.com/gogits/gogs/modules/auth/ldap"
 	"github.com/gogits/gogs/modules/auth/pam"
 )
@@ -394,7 +394,7 @@ func SMTPAuth(a smtp.Auth, cfg *SMTPConfig) error {
 		}
 		return nil
 	}
-	return ErrUnsupportedLoginType
+	return errors.New("Unsupported SMTP authentication method")
 }
 
 // LoginViaSMTP queries if login/password is valid against the SMTP,
@@ -416,7 +416,7 @@ func LoginViaSMTP(user *User, login, password string, sourceID int64, cfg *SMTPC
 	} else if cfg.Auth == SMTP_LOGIN {
 		auth = &smtpLoginAuth{login, password}
 	} else {
-		return nil, errors.New("Unsupported SMTP auth type")
+		return nil, errors.New("Unsupported SMTP authentication type")
 	}
 
 	if err := SMTPAuth(auth, cfg); err != nil {
@@ -489,7 +489,7 @@ func LoginViaPAM(user *User, login, password string, sourceID int64, cfg *PAMCon
 
 func ExternalUserLogin(user *User, login, password string, source *LoginSource, autoRegister bool) (*User, error) {
 	if !source.IsActived {
-		return nil, ErrLoginSourceNotActived
+		return nil, errors.LoginSourceNotActivated{source.ID}
 	}
 
 	switch source.Type {
@@ -501,7 +501,7 @@ func ExternalUserLogin(user *User, login, password string, source *LoginSource,
 		return LoginViaPAM(user, login, password, source.ID, source.Cfg.(*PAMConfig), autoRegister)
 	}
 
-	return nil, ErrUnsupportedLoginType
+	return nil, errors.InvalidLoginSourceType{source.Type}
 }
 
 // UserSignIn validates user name and password.
diff --git a/models/mirror.go b/models/mirror.go
index a1c14e04e..2107bc07b 100644
--- a/models/mirror.go
+++ b/models/mirror.go
@@ -16,6 +16,7 @@ import (
 
 	"github.com/gogits/git-module"
 
+	"github.com/gogits/gogs/models/errors"
 	"github.com/gogits/gogs/modules/process"
 	"github.com/gogits/gogs/modules/setting"
 	"github.com/gogits/gogs/modules/sync"
@@ -185,7 +186,7 @@ func getMirrorByRepoID(e Engine, repoID int64) (*Mirror, error) {
 	if err != nil {
 		return nil, err
 	} else if !has {
-		return nil, ErrMirrorNotExist
+		return nil, errors.MirrorNotExist{repoID}
 	}
 	return m, nil
 }
diff --git a/models/repo.go b/models/repo.go
index 7fee5154d..23213b66a 100644
--- a/models/repo.go
+++ b/models/repo.go
@@ -6,7 +6,6 @@ package models
 
 import (
 	"bytes"
-	"errors"
 	"fmt"
 	"html/template"
 	"io/ioutil"
@@ -29,6 +28,7 @@ import (
 	git "github.com/gogits/git-module"
 	api "github.com/gogits/go-gogs-client"
 
+	"github.com/gogits/gogs/models/errors"
 	"github.com/gogits/gogs/modules/bindata"
 	"github.com/gogits/gogs/modules/markdown"
 	"github.com/gogits/gogs/modules/process"
@@ -38,14 +38,6 @@ import (
 
 var repoWorkingPool = sync.NewExclusivePool()
 
-var (
-	ErrRepoFileNotExist  = errors.New("Repository file does not exist")
-	ErrRepoFileNotLoaded = errors.New("Repository file not loaded")
-	ErrMirrorNotExist    = errors.New("Mirror does not exist")
-	ErrInvalidReference  = errors.New("Invalid reference specified")
-	ErrNameEmpty         = errors.New("Name is empty")
-)
-
 var (
 	Gitignores, Licenses, Readmes, LabelTemplates []string
 
@@ -1028,7 +1020,7 @@ func CreateRepository(doer, owner *User, opts CreateRepoOptions) (_ *Repository,
 			repoPath, fmt.Sprintf("CreateRepository 'git update-server-info': %s", repoPath),
 			"git", "update-server-info")
 		if err != nil {
-			return nil, errors.New("CreateRepository 'git update-server-info': " + stderr)
+			return nil, fmt.Errorf("CreateRepository 'git update-server-info': %s", stderr)
 		}
 	}
 
@@ -1474,7 +1466,7 @@ func DeleteRepository(uid, repoID int64) error {
 func GetRepositoryByRef(ref string) (*Repository, error) {
 	n := strings.IndexByte(ref, byte('/'))
 	if n < 2 {
-		return nil, ErrInvalidReference
+		return nil, errors.InvalidRepoReference{ref}
 	}
 
 	userName, repoName := ref[:n], ref[n+1:]
diff --git a/models/user.go b/models/user.go
index 993c69dc0..2737d375f 100644
--- a/models/user.go
+++ b/models/user.go
@@ -10,7 +10,6 @@ import (
 	"crypto/sha256"
 	"crypto/subtle"
 	"encoding/hex"
-	"errors"
 	"fmt"
 	"image"
 	_ "image/jpeg"
@@ -30,6 +29,7 @@ import (
 	"github.com/gogits/git-module"
 	api "github.com/gogits/go-gogs-client"
 
+	"github.com/gogits/gogs/models/errors"
 	"github.com/gogits/gogs/modules/avatar"
 	"github.com/gogits/gogs/modules/base"
 	"github.com/gogits/gogs/modules/markdown"
@@ -43,15 +43,6 @@ const (
 	USER_TYPE_ORGANIZATION
 )
 
-var (
-	ErrUserNotKeyOwner       = errors.New("User does not the owner of public key")
-	ErrEmailNotExist         = errors.New("E-mail does not exist")
-	ErrEmailNotActivated     = errors.New("E-mail address has not been activated")
-	ErrUserNameIllegal       = errors.New("User name contains illegal characters")
-	ErrLoginSourceNotActived = errors.New("Login source is not actived")
-	ErrUnsupportedLoginType  = errors.New("Login source is unknown")
-)
-
 // User represents the object of individual and member of organization.
 type User struct {
 	ID        int64  `xorm:"pk autoincr"`
@@ -519,7 +510,7 @@ var (
 func isUsableName(names, patterns []string, name string) error {
 	name = strings.TrimSpace(strings.ToLower(name))
 	if utf8.RuneCountInString(name) == 0 {
-		return ErrNameEmpty
+		return errors.EmptyName{}
 	}
 
 	for i := range names {
@@ -890,11 +881,11 @@ func UserPath(userName string) string {
 
 func GetUserByKeyID(keyID int64) (*User, error) {
 	user := new(User)
-	has, err := x.Sql("SELECT a.* FROM `user` AS a, public_key AS b WHERE a.id = b.owner_id AND b.id=?", keyID).Get(user)
+	has, err := x.SQL("SELECT a.* FROM `user` AS a, public_key AS b WHERE a.id = b.owner_id AND b.id=?", keyID).Get(user)
 	if err != nil {
 		return nil, err
 	} else if !has {
-		return nil, ErrUserNotKeyOwner
+		return nil, errors.UserNotKeyOwner{keyID}
 	}
 	return user, nil
 }
diff --git a/models/user_mail.go b/models/user_mail.go
index 4c6efd423..b1b23ee34 100644
--- a/models/user_mail.go
+++ b/models/user_mail.go
@@ -7,6 +7,8 @@ package models
 import (
 	"fmt"
 	"strings"
+
+	"github.com/gogits/gogs/models/errors"
 )
 
 // EmailAdresses is the list of all email addresses of a user. Can contain the
@@ -163,11 +165,11 @@ func MakeEmailPrimary(email *EmailAddress) error {
 	if err != nil {
 		return err
 	} else if !has {
-		return ErrEmailNotExist
+		return errors.EmailNotFound{email.Email}
 	}
 
 	if !email.IsActivated {
-		return ErrEmailNotActivated
+		return errors.EmailNotVerified{email.Email}
 	}
 
 	user := &User{ID: email.UID}
diff --git a/routers/org/setting.go b/routers/org/setting.go
index 136e1b663..ae16854ab 100644
--- a/routers/org/setting.go
+++ b/routers/org/setting.go
@@ -51,10 +51,13 @@ func SettingsPost(ctx *context.Context, f form.UpdateOrgSetting) {
 			ctx.RenderWithErr(ctx.Tr("form.username_been_taken"), SETTINGS_OPTIONS, &f)
 			return
 		} else if err = models.ChangeUserName(org, f.Name); err != nil {
-			if err == models.ErrUserNameIllegal {
-				ctx.Data["OrgName"] = true
-				ctx.RenderWithErr(ctx.Tr("form.illegal_username"), SETTINGS_OPTIONS, &f)
-			} else {
+			ctx.Data["OrgName"] = true
+			switch {
+			case models.IsErrNameReserved(err):
+				ctx.RenderWithErr(ctx.Tr("user.form.name_reserved"), SETTINGS_OPTIONS, &f)
+			case models.IsErrNamePatternNotAllowed(err):
+				ctx.RenderWithErr(ctx.Tr("user.form.name_pattern_not_allowed"), SETTINGS_OPTIONS, &f)
+			default:
 				ctx.Handle(500, "ChangeUserName", err)
 			}
 			return