diff --git a/models/migrations/migrations.go b/models/migrations/migrations.go
index 3227f6f75451b..3e2a799701690 100644
--- a/models/migrations/migrations.go
+++ b/models/migrations/migrations.go
@@ -281,6 +281,8 @@ var migrations = []Migration{
 	NewMigration("Where Password is Valid with Empty String delete it", recalculateUserEmptyPWD),
 	// v167 -> v168
 	NewMigration("Add user redirect", addUserRedirect),
+	// v168 -> v169
+	NewMigration("Recreate user table to fix default values", recreateUserTableToFixDefaultValues),
 }
 
 // GetCurrentDBVersion returns the current db version
diff --git a/models/migrations/v141.go b/models/migrations/v141.go
index b5824ecd48db2..ab05698b8cb5d 100644
--- a/models/migrations/v141.go
+++ b/models/migrations/v141.go
@@ -12,7 +12,7 @@ import (
 
 func addKeepActivityPrivateUserColumn(x *xorm.Engine) error {
 	type User struct {
-		KeepActivityPrivate bool
+		KeepActivityPrivate bool `xorm:"NOT NULL DEFAULT false"`
 	}
 
 	if err := x.Sync2(new(User)); err != nil {
diff --git a/models/migrations/v168.go b/models/migrations/v168.go
new file mode 100644
index 0000000000000..246b120d33939
--- /dev/null
+++ b/models/migrations/v168.go
@@ -0,0 +1,106 @@
+// Copyright 2021 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/builder"
+	"xorm.io/xorm"
+	"xorm.io/xorm/schemas"
+)
+
+func recreateUserTableToFixDefaultValues(x *xorm.Engine) error {
+	type User struct {
+		ID                           int64  `xorm:"pk autoincr"`
+		LowerName                    string `xorm:"UNIQUE NOT NULL"`
+		Name                         string `xorm:"UNIQUE NOT NULL"`
+		FullName                     string
+		Email                        string `xorm:"NOT NULL"`
+		KeepEmailPrivate             bool
+		EmailNotificationsPreference string `xorm:"VARCHAR(20) NOT NULL DEFAULT 'enabled'"`
+		Passwd                       string `xorm:"NOT NULL"`
+		PasswdHashAlgo               string `xorm:"NOT NULL DEFAULT 'argon2'"`
+
+		MustChangePassword bool `xorm:"NOT NULL DEFAULT false"`
+
+		LoginType   int
+		LoginSource int64 `xorm:"NOT NULL DEFAULT 0"`
+		LoginName   string
+		Type        int
+		Location    string
+		Website     string
+		Rands       string `xorm:"VARCHAR(10)"`
+		Salt        string `xorm:"VARCHAR(10)"`
+		Language    string `xorm:"VARCHAR(5)"`
+		Description string
+
+		CreatedUnix   int64 `xorm:"INDEX created"`
+		UpdatedUnix   int64 `xorm:"INDEX updated"`
+		LastLoginUnix int64 `xorm:"INDEX"`
+
+		LastRepoVisibility bool
+		MaxRepoCreation    int `xorm:"NOT NULL DEFAULT -1"`
+
+		// Permissions
+		IsActive                bool `xorm:"INDEX"`
+		IsAdmin                 bool
+		IsRestricted            bool `xorm:"NOT NULL DEFAULT false"`
+		AllowGitHook            bool
+		AllowImportLocal        bool
+		AllowCreateOrganization bool `xorm:"DEFAULT true"`
+		ProhibitLogin           bool `xorm:"NOT NULL DEFAULT false"`
+
+		// Avatar
+		Avatar          string `xorm:"VARCHAR(2048) NOT NULL"`
+		AvatarEmail     string `xorm:"NOT NULL"`
+		UseCustomAvatar bool
+
+		// Counters
+		NumFollowers int
+		NumFollowing int `xorm:"NOT NULL DEFAULT 0"`
+		NumStars     int
+		NumRepos     int
+
+		// For organization
+		NumTeams                  int
+		NumMembers                int
+		Visibility                int  `xorm:"NOT NULL DEFAULT 0"`
+		RepoAdminChangeTeamAccess bool `xorm:"NOT NULL DEFAULT false"`
+
+		// Preferences
+		DiffViewStyle       string `xorm:"NOT NULL DEFAULT ''"`
+		Theme               string `xorm:"NOT NULL DEFAULT ''"`
+		KeepActivityPrivate bool   `xorm:"NOT NULL DEFAULT false"`
+	}
+
+	if _, err := x.Where(builder.IsNull{"keep_activity_private"}).
+		Cols("keep_activity_private").
+		Update(User{KeepActivityPrivate: false}); err != nil {
+		return err
+	}
+
+	switch x.Dialect().URI().DBType {
+	case schemas.MYSQL:
+		_, err := x.Exec("ALTER TABLE `user` MODIFY COLUMN keep_activity_private tinyint(1) DEFAULT 0 NOT NULL;")
+		return err
+	case schemas.POSTGRES:
+		if _, err := x.Exec("ALTER TABLE `user` ALTER COLUMN keep_activity_private SET NOT NULL;"); err != nil {
+			return err
+		}
+		_, err := x.Exec("ALTER TABLE `user` ALTER COLUMN keep_activity_private SET DEFAULT false;")
+		return err
+	}
+
+	sess := x.NewSession()
+	defer sess.Close()
+	if err := sess.Begin(); err != nil {
+		return err
+	}
+
+	if err := recreateTable(sess, new(User)); err != nil {
+		return err
+	}
+
+	return sess.Commit()
+}