diff --git a/api/v2.0/swagger.yaml b/api/v2.0/swagger.yaml
index 85ab299a1..b4ef459f8 100644
--- a/api/v2.0/swagger.yaml
+++ b/api/v2.0/swagger.yaml
@@ -6135,6 +6135,7 @@ definitions:
       project_name:
         type: string
         description: The name of the project.
+        maxLength: 255
       public:
         type: boolean
         description: deprecated, reserved for project creation in replication
@@ -8023,6 +8024,7 @@ definitions:
     properties:
       email:
         type: string
+        maxLength: 255
       realname:
         type: string
       comment:
@@ -8031,6 +8033,7 @@ definitions:
         type: string
       username:
         type: string
+        maxLength: 255
   OIDCUserInfo:
     type: object
     properties:
diff --git a/src/lib/truncate.go b/src/lib/truncate.go
new file mode 100644
index 000000000..2deb9f2e7
--- /dev/null
+++ b/src/lib/truncate.go
@@ -0,0 +1,25 @@
+// Copyright Project Harbor Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package lib
+
+// Truncate tries to append the "suffix" to the "str". If the length of the appended string exceeds "n",
+// the function truncates the "str" to make sure the "suffix" is appended
+func Truncate(str, suffix string, n int) string {
+	s := str + suffix
+	if len(s) <= n {
+		return s
+	}
+	return s[:len(str)-(len(s)-n)] + suffix
+}
diff --git a/src/lib/truncate_test.go b/src/lib/truncate_test.go
new file mode 100644
index 000000000..92bf12599
--- /dev/null
+++ b/src/lib/truncate_test.go
@@ -0,0 +1,42 @@
+// Copyright Project Harbor Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package lib
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestTruncate(t *testing.T) {
+	assert := assert.New(t)
+
+	// n > length
+	str := "abc"
+	suffix := "#123"
+	n := 10
+	assert.Equal("abc#123", Truncate(str, suffix, n))
+
+	// n == length
+	str = "abc"
+	suffix = "#123"
+	n = 7
+	assert.Equal("abc#123", Truncate(str, suffix, n))
+
+	// n < length
+	str = "abc"
+	suffix = "#123"
+	n = 5
+	assert.Equal("a#123", Truncate(str, suffix, n))
+}
diff --git a/src/pkg/project/dao/dao.go b/src/pkg/project/dao/dao.go
index ddbebe28d..420f4e77f 100644
--- a/src/pkg/project/dao/dao.go
+++ b/src/pkg/project/dao/dao.go
@@ -20,6 +20,7 @@ import (
 	"time"
 
 	"github.com/goharbor/harbor/src/common"
+	"github.com/goharbor/harbor/src/lib"
 	"github.com/goharbor/harbor/src/lib/orm"
 	"github.com/goharbor/harbor/src/lib/q"
 	"github.com/goharbor/harbor/src/pkg/project/models"
@@ -112,7 +113,7 @@ func (d *dao) Delete(ctx context.Context, id int64) error {
 	}
 
 	project.Deleted = true
-	project.Name = fmt.Sprintf("%s#%d", project.Name, project.ProjectID)
+	project.Name = lib.Truncate(project.Name, fmt.Sprintf("#%d", project.ProjectID), 255)
 
 	o, err := orm.FromContext(ctx)
 	if err != nil {
diff --git a/src/pkg/user/manager.go b/src/pkg/user/manager.go
index 57465a48a..9fcfef32e 100644
--- a/src/pkg/user/manager.go
+++ b/src/pkg/user/manager.go
@@ -20,6 +20,7 @@ import (
 	"strings"
 
 	"github.com/goharbor/harbor/src/common/utils"
+	"github.com/goharbor/harbor/src/lib"
 	"github.com/goharbor/harbor/src/lib/errors"
 	"github.com/goharbor/harbor/src/lib/q"
 	"github.com/goharbor/harbor/src/pkg/user/dao"
@@ -70,8 +71,8 @@ func (m *manager) Delete(ctx context.Context, id int) error {
 	if err != nil {
 		return err
 	}
-	u.Username = fmt.Sprintf("%s#%d", u.Username, u.UserID)
-	u.Email = fmt.Sprintf("%s#%d", u.Email, u.UserID)
+	u.Username = lib.Truncate(u.Username, fmt.Sprintf("#%d", u.UserID), 255)
+	u.Email = lib.Truncate(u.Email, fmt.Sprintf("#%d", u.UserID), 255)
 	u.Deleted = true
 	return m.dao.Update(ctx, u, "username", "email", "deleted")
 }