2 files changed, 25 insertions, 2 deletions
diff --git a/modules/json/json.go b/modules/json/json.go
index 34568c75c6..444dc8526a 100644
--- a/modules/json/json.go
+++ b/modules/json/json.go
@@ -3,11 +3,10 @@
 
 package json
 
-// Allow "encoding/json" import.
 import (
 	"bytes"
 	"encoding/binary"
-	"encoding/json" //nolint:depguard
+	"encoding/json" //nolint:depguard // this package wraps it
 	"io"
 
 	jsoniter "github.com/json-iterator/go"
@@ -145,6 +144,12 @@ func Valid(data []byte) bool {
 // UnmarshalHandleDoubleEncode - due to a bug in xorm (see https://gitea.com/xorm/xorm/pulls/1957) - it's
 // possible that a Blob may be double encoded or gain an unwanted prefix of 0xff 0xfe.
 func UnmarshalHandleDoubleEncode(bs []byte, v any) error {
+	if len(bs) == 0 {
+		// json.Unmarshal will report errors if input is empty (nil or zero-length)
+		// It seems that XORM ignores the nil but still passes zero-length string into this function
+		// To be consistent, we should treat all empty inputs as success
+		return nil
+	}
 	err := json.Unmarshal(bs, v)
 	if err != nil {
 		ok := true
diff --git a/modules/json/json_test.go b/modules/json/json_test.go
new file mode 100644
index 0000000000..ace7167913
--- /dev/null
+++ b/modules/json/json_test.go
@@ -0,0 +1,18 @@
+// Copyright 2025 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package json
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGiteaDBJSONUnmarshal(t *testing.T) {
+	var m map[any]any
+	err := UnmarshalHandleDoubleEncode(nil, &m)
+	assert.NoError(t, err)
+	err = UnmarshalHandleDoubleEncode([]byte(""), &m)
+	assert.NoError(t, err)
+}