diff --git a/.deadcode-out b/.deadcode-out
index 9641f272b3..dd81cc6c3f 100644
--- a/.deadcode-out
+++ b/.deadcode-out
@@ -204,6 +204,7 @@ forgejo.org/modules/util/filebuffer
 
 forgejo.org/modules/validation
 	IsErrNotValid
+	ValidateIDExists
 
 forgejo.org/modules/web
 	RouteMock
diff --git a/modules/forgefed/activity_like_test.go b/modules/forgefed/activity_like_test.go
index f4cb7e4e00..6b252d5960 100644
--- a/modules/forgefed/activity_like_test.go
+++ b/modules/forgefed/activity_like_test.go
@@ -143,7 +143,7 @@ func Test_ForgeLikeValidation(t *testing.T) {
 		"actor":"https://repo.prod.meissa.de/api/activitypub/user-id/1",
 	"object":"https://codeberg.org/api/activitypub/repository-id/1",
 	"startTime": "2014-12-31T23:00:00-08:00"}`))
-	if err := validateAndCheckError(sut, "Value bad-type is not contained in allowed values [Like]"); err != nil {
+	if err := validateAndCheckError(sut, "Field type contains the value bad-type, which is not in allowed subset [Like]"); err != nil {
 		t.Error(err)
 	}
 
@@ -154,14 +154,6 @@ func Test_ForgeLikeValidation(t *testing.T) {
 	if err := validateAndCheckError(sut, "StartTime was invalid."); err != nil {
 		t.Error(err)
 	}
-
-	sut.UnmarshalJSON([]byte(`{"type":"Wrong",
-		"actor":"https://repo.prod.meissa.de/api/activitypub/user-id/1",
-	  "object":"https://codeberg.org/api/activitypub/repository-id/1",
-	  "startTime": "2014-12-31T23:00:00-08:00"}`))
-	if err := validateAndCheckError(sut, "Value Wrong is not contained in allowed values [Like]"); err != nil {
-		t.Error(err)
-	}
 }
 
 func TestActivityValidation_Attack(t *testing.T) {
diff --git a/modules/forgefed/actor_test.go b/modules/forgefed/actor_test.go
index 10b6578953..4d58cfd806 100644
--- a/modules/forgefed/actor_test.go
+++ b/modules/forgefed/actor_test.go
@@ -145,7 +145,7 @@ func TestPersonIdValidation(t *testing.T) {
 	sut.HostPort = 443
 	sut.IsPortSupplemented = true
 	sut.UnvalidatedInput = "https://an.other.host/api/v1/activitypub/user-id/1"
-	if sut.Validate()[0] != "Value forgejox is not contained in allowed values [forgejo gitea]" {
+	if sut.Validate()[0] != "Field Source contains the value forgejox, which is not in allowed subset [forgejo gitea]" {
 		t.Errorf("validation error expected but was: %v\n", sut.Validate()[0])
 	}
 }
diff --git a/modules/validation/validatable.go b/modules/validation/validatable.go
index d2c5553259..4500f6e53d 100644
--- a/modules/validation/validatable.go
+++ b/modules/validation/validatable.go
@@ -10,6 +10,8 @@ import (
 	"unicode/utf8"
 
 	"forgejo.org/modules/timeutil"
+
+	ap "github.com/go-ap/activitypub"
 )
 
 // ErrNotValid represents an validation error
@@ -41,6 +43,13 @@ func IsValid(v Validateable) (bool, error) {
 	return true, nil
 }
 
+func ValidateIDExists(value ap.Item, name string) []string {
+	if value == nil {
+		return []string{fmt.Sprintf("%v should not be nil", name)}
+	}
+	return ValidateNotEmpty(value.GetID().String(), name)
+}
+
 func ValidateNotEmpty(value any, name string) []string {
 	isValid := true
 	switch v := value.(type) {
@@ -83,5 +92,5 @@ func ValidateOneOf(value any, allowed []any, name string) []string {
 			return []string{}
 		}
 	}
-	return []string{fmt.Sprintf("Value %v is not contained in allowed values %v", value, allowed)}
+	return []string{fmt.Sprintf("Field %s contains the value %v, which is not in allowed subset %v", name, value, allowed)}
 }
diff --git a/modules/validation/validatable_test.go b/modules/validation/validatable_test.go
index c843afe702..1fe407b343 100644
--- a/modules/validation/validatable_test.go
+++ b/modules/validation/validatable_test.go
@@ -1,4 +1,4 @@
-// Copyright 2024 The Forgejo Authors. All rights reserved.
+// Copyright 2024, 2025 The Forgejo Authors. All rights reserved.
 // SPDX-License-Identifier: MIT
 
 package validation
@@ -7,6 +7,9 @@ import (
 	"testing"
 
 	"forgejo.org/modules/timeutil"
+
+	ap "github.com/go-ap/activitypub"
+	"github.com/stretchr/testify/assert"
 )
 
 type Sut struct {
@@ -37,33 +40,50 @@ func Test_IsValid(t *testing.T) {
 
 func Test_ValidateNotEmpty_ForString(t *testing.T) {
 	sut := ""
-	if len(ValidateNotEmpty(sut, "dummyField")) == 0 {
-		t.Error("sut should be invalid")
-	}
+	res := ValidateNotEmpty(sut, "dummyField")
+	assert.Len(t, res, 1)
+
 	sut = "not empty"
-	if res := ValidateNotEmpty(sut, "dummyField"); len(res) > 0 {
-		t.Errorf("sut should be valid but was %q", res)
-	}
+	res = ValidateNotEmpty(sut, "dummyField")
+	assert.Empty(t, res, 0)
 }
 
 func Test_ValidateNotEmpty_ForTimestamp(t *testing.T) {
 	sut := timeutil.TimeStamp(0)
-	if res := ValidateNotEmpty(sut, "dummyField"); len(res) == 0 {
-		t.Error("sut should be invalid")
-	}
+	res := ValidateNotEmpty(sut, "dummyField")
+	assert.Len(t, res, 1)
+
 	sut = timeutil.TimeStampNow()
-	if res := ValidateNotEmpty(sut, "dummyField"); len(res) > 0 {
-		t.Errorf("sut should be valid but was %q", res)
+	res = ValidateNotEmpty(sut, "dummyField")
+	assert.Empty(t, res, 0)
+}
+
+func Test_ValidateIDExists_ForItem(t *testing.T) {
+	sut := ap.Activity{
+		Object: nil,
 	}
+	res := ValidateIDExists(sut.Object, "dummyField")
+	assert.Len(t, res, 1)
+
+	sut = ap.Activity{
+		Object: ap.IRI(""),
+	}
+	res = ValidateIDExists(sut.Object, "dummyField")
+	assert.Len(t, res, 1)
+
+	sut = ap.Activity{
+		Object: ap.IRI("https://dummy.link/id"),
+	}
+	res = ValidateIDExists(sut.Object, "dummyField")
+	assert.Empty(t, res, 0)
 }
 
 func Test_ValidateMaxLen(t *testing.T) {
 	sut := "0123456789"
-	if len(ValidateMaxLen(sut, 9, "dummyField")) == 0 {
-		t.Error("sut should be invalid")
-	}
+	res := ValidateMaxLen(sut, 9, "dummyField")
+	assert.Len(t, res, 1)
+
 	sut = "0123456789"
-	if res := ValidateMaxLen(sut, 11, "dummyField"); len(res) > 0 {
-		t.Errorf("sut should be valid but was %q", res)
-	}
+	res = ValidateMaxLen(sut, 11, "dummyField")
+	assert.Empty(t, res, 0)
 }