diff --git a/models/migrations/migrations.go b/models/migrations/migrations.go
index bb3adccc257..4f3d823b9af 100644
--- a/models/migrations/migrations.go
+++ b/models/migrations/migrations.go
@@ -6,6 +6,7 @@
 package migrations
 
 import (
+	"context"
 	"fmt"
 	"os"
 	"reflect"
@@ -16,6 +17,7 @@ import (
 	"code.gitea.io/gitea/modules/setting"
 
 	"xorm.io/xorm"
+	"xorm.io/xorm/schemas"
 )
 
 const minDBVersion = 70 // Gitea 1.5.3
@@ -273,6 +275,8 @@ var migrations = []Migration{
 	NewMigration("Convert topic name from 25 to 50", convertTopicNameFrom25To50),
 	// v164 -> v165
 	NewMigration("Add scope and nonce columns to oauth2_grant table", addScopeAndNonceColumnsToOAuth2Grant),
+	// v165 -> v166
+	NewMigration("Convert hook task type from char(16) to varchar(16) and trim the column", convertHookTaskTypeToVarcharAndTrim),
 }
 
 // GetCurrentDBVersion returns the current db version
@@ -737,3 +741,39 @@ func dropTableColumns(sess *xorm.Session, tableName string, columnNames ...strin
 
 	return nil
 }
+
+// modifyColumn will modify column's type or other propertity. SQLITE is not supported
+func modifyColumn(x *xorm.Engine, tableName string, col *schemas.Column) error {
+	var indexes map[string]*schemas.Index
+	var err error
+	// MSSQL have to remove index at first, otherwise alter column will fail
+	// ref. https://sqlzealots.com/2018/05/09/error-message-the-index-is-dependent-on-column-alter-table-alter-column-failed-because-one-or-more-objects-access-this-column/
+	if x.Dialect().URI().DBType == schemas.MSSQL {
+		indexes, err = x.Dialect().GetIndexes(x.DB(), context.Background(), tableName)
+		if err != nil {
+			return err
+		}
+
+		for _, index := range indexes {
+			_, err = x.Exec(x.Dialect().DropIndexSQL(tableName, index))
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	defer func() {
+		for _, index := range indexes {
+			_, err = x.Exec(x.Dialect().CreateIndexSQL(tableName, index))
+			if err != nil {
+				log.Error("Create index %s on table %s failed: %v", index.Name, tableName, err)
+			}
+		}
+	}()
+
+	alterSQL := x.Dialect().ModifyColumnSQL(tableName, col)
+	if _, err := x.Exec(alterSQL); err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/models/migrations/v161.go b/models/migrations/v161.go
index 127dca15007..3eff7df8a3b 100644
--- a/models/migrations/v161.go
+++ b/models/migrations/v161.go
@@ -34,7 +34,7 @@ func convertTaskTypeToString(x *xorm.Engine) error {
 	}
 
 	type HookTask struct {
-		Typ string `xorm:"char(16) index"`
+		Typ string `xorm:"VARCHAR(16) index"`
 	}
 	if err := x.Sync2(new(HookTask)); err != nil {
 		return err
diff --git a/models/migrations/v165.go b/models/migrations/v165.go
new file mode 100644
index 00000000000..d7df0f07a97
--- /dev/null
+++ b/models/migrations/v165.go
@@ -0,0 +1,66 @@
+// Copyright 2020 The Gitea 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 migrations
+
+import (
+	"xorm.io/xorm"
+	"xorm.io/xorm/schemas"
+)
+
+func convertHookTaskTypeToVarcharAndTrim(x *xorm.Engine) error {
+	dbType := x.Dialect().URI().DBType
+	if dbType == schemas.SQLITE { // For SQLITE, varchar or char will always be represented as TEXT
+		return nil
+	}
+
+	type HookTask struct {
+		Typ string `xorm:"VARCHAR(16) index"`
+	}
+
+	if err := modifyColumn(x, "hook_task", &schemas.Column{
+		Name: "typ",
+		SQLType: schemas.SQLType{
+			Name: "VARCHAR",
+		},
+		Length:   16,
+		Nullable: true, // To keep compatible as nullable
+	}); err != nil {
+		return err
+	}
+
+	var hookTaskTrimSQL string
+	if dbType == schemas.MSSQL {
+		hookTaskTrimSQL = "UPDATE hook_task SET typ = RTRIM(LTRIM(typ))"
+	} else {
+		hookTaskTrimSQL = "UPDATE hook_task SET typ = TRIM(typ)"
+	}
+	if _, err := x.Exec(hookTaskTrimSQL); err != nil {
+		return err
+	}
+
+	type Webhook struct {
+		Type string `xorm:"VARCHAR(16) index"`
+	}
+
+	if err := modifyColumn(x, "webhook", &schemas.Column{
+		Name: "type",
+		SQLType: schemas.SQLType{
+			Name: "VARCHAR",
+		},
+		Length:   16,
+		Nullable: true, // To keep compatible as nullable
+	}); err != nil {
+		return err
+	}
+
+	var webhookTrimSQL string
+	if dbType == schemas.MSSQL {
+		webhookTrimSQL = "UPDATE webhook SET type = RTRIM(LTRIM(type))"
+	} else {
+		webhookTrimSQL = "UPDATE webhook SET type = TRIM(type)"
+	}
+	_, err := x.Exec(webhookTrimSQL)
+	return err
+}
diff --git a/models/webhook.go b/models/webhook.go
index 9f1b6131afc..e0a75843db8 100644
--- a/models/webhook.go
+++ b/models/webhook.go
@@ -113,7 +113,7 @@ type Webhook struct {
 	*HookEvent      `xorm:"-"`
 	IsSSL           bool         `xorm:"is_ssl"`
 	IsActive        bool         `xorm:"INDEX"`
-	Type            HookTaskType `xorm:"char(16) 'type'"`
+	Type            HookTaskType `xorm:"VARCHAR(16) 'type'"`
 	Meta            string       `xorm:"TEXT"` // store hook-specific attributes
 	LastStatus      HookStatus   // Last delivery status
 
@@ -641,9 +641,9 @@ type HookTask struct {
 	RepoID          int64 `xorm:"INDEX"`
 	HookID          int64
 	UUID            string
-	Typ             HookTaskType
-	URL             string `xorm:"TEXT"`
-	Signature       string `xorm:"TEXT"`
+	Typ             HookTaskType `xorm:"VARCHAR(16) index"`
+	URL             string       `xorm:"TEXT"`
+	Signature       string       `xorm:"TEXT"`
 	api.Payloader   `xorm:"-"`
 	PayloadContent  string `xorm:"TEXT"`
 	HTTPMethod      string `xorm:"http_method"`
diff --git a/services/webhook/webhook.go b/services/webhook/webhook.go
index b779b38466a..7b6bc555f73 100644
--- a/services/webhook/webhook.go
+++ b/services/webhook/webhook.go
@@ -60,7 +60,7 @@ var (
 
 // RegisterWebhook registers a webhook
 func RegisterWebhook(name string, webhook *webhook) {
-	webhooks[models.HookTaskType(strings.TrimSpace(name))] = webhook
+	webhooks[models.HookTaskType(name)] = webhook
 }
 
 // IsValidHookTaskType returns true if a webhook registered
@@ -68,7 +68,7 @@ func IsValidHookTaskType(name string) bool {
 	if name == models.GITEA || name == models.GOGS {
 		return true
 	}
-	_, ok := webhooks[models.HookTaskType(strings.TrimSpace(name))]
+	_, ok := webhooks[models.HookTaskType(name)]
 	return ok
 }
 
@@ -147,7 +147,7 @@ func prepareWebhook(w *models.Webhook, repo *models.Repository, event models.Hoo
 
 	var payloader api.Payloader
 	var err error
-	webhook, ok := webhooks[strings.TrimSpace(w.Type)] // NOTICE: w.Type maynot be trimmed before store into database
+	webhook, ok := webhooks[w.Type]
 	if ok {
 		payloader, err = webhook.payloadCreator(p, event, w.Meta)
 		if err != nil {