2 files changed, 135 insertions, 0 deletions
diff --git a/weed/s3api/s3_constants/header.go b/weed/s3api/s3_constants/header.go
index b7e1be9e5..4b34f397e 100644
--- a/weed/s3api/s3_constants/header.go
+++ b/weed/s3api/s3_constants/header.go
@@ -146,7 +146,10 @@ func GetBucketAndObject(r *http.Request) (bucket, object string) {
 
 // NormalizeObjectKey ensures the object key has a leading slash and no duplicate slashes.
 // This normalizes keys from various sources (URL path, form values, etc.) to a consistent format.
+// It also converts Windows-style backslashes to forward slashes for cross-platform compatibility.
 func NormalizeObjectKey(object string) string {
+	// Convert Windows-style backslashes to forward slashes
+	object = strings.ReplaceAll(object, "\\", "/")
 	object = removeDuplicateSlashes(object)
 	if !strings.HasPrefix(object, "/") {
 		object = "/" + object
diff --git a/weed/s3api/s3_constants/header_test.go b/weed/s3api/s3_constants/header_test.go
new file mode 100644
index 000000000..b16cfc6a8
--- /dev/null
+++ b/weed/s3api/s3_constants/header_test.go
@@ -0,0 +1,132 @@
+package s3_constants
+
+import (
+	"testing"
+)
+
+func TestNormalizeObjectKey(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+	}{
+		{
+			name:     "simple key",
+			input:    "file.txt",
+			expected: "/file.txt",
+		},
+		{
+			name:     "key with leading slash",
+			input:    "/file.txt",
+			expected: "/file.txt",
+		},
+		{
+			name:     "key with directory",
+			input:    "folder/file.txt",
+			expected: "/folder/file.txt",
+		},
+		{
+			name:     "key with leading slash and directory",
+			input:    "/folder/file.txt",
+			expected: "/folder/file.txt",
+		},
+		{
+			name:     "key with duplicate slashes",
+			input:    "folder//subfolder///file.txt",
+			expected: "/folder/subfolder/file.txt",
+		},
+		{
+			name:     "Windows backslash - simple",
+			input:    "folder\\file.txt",
+			expected: "/folder/file.txt",
+		},
+		{
+			name:     "Windows backslash - nested",
+			input:    "folder\\subfolder\\file.txt",
+			expected: "/folder/subfolder/file.txt",
+		},
+		{
+			name:     "Windows backslash - with leading slash",
+			input:    "/folder\\subfolder\\file.txt",
+			expected: "/folder/subfolder/file.txt",
+		},
+		{
+			name:     "mixed slashes",
+			input:    "folder\\subfolder/another\\file.txt",
+			expected: "/folder/subfolder/another/file.txt",
+		},
+		{
+			name:     "Windows full path style (edge case)",
+			input:    "C:\\Users\\test\\file.txt",
+			expected: "/C:/Users/test/file.txt",
+		},
+		{
+			name:     "empty string",
+			input:    "",
+			expected: "/",
+		},
+		{
+			name:     "just a slash",
+			input:    "/",
+			expected: "/",
+		},
+		{
+			name:     "just a backslash",
+			input:    "\\",
+			expected: "/",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := NormalizeObjectKey(tt.input)
+			if result != tt.expected {
+				t.Errorf("NormalizeObjectKey(%q) = %q, want %q", tt.input, result, tt.expected)
+			}
+		})
+	}
+}
+
+func TestRemoveDuplicateSlashes(t *testing.T) {
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+	}{
+		{
+			name:     "no duplicates",
+			input:    "/folder/file.txt",
+			expected: "/folder/file.txt",
+		},
+		{
+			name:     "double slash",
+			input:    "/folder//file.txt",
+			expected: "/folder/file.txt",
+		},
+		{
+			name:     "triple slash",
+			input:    "/folder///file.txt",
+			expected: "/folder/file.txt",
+		},
+		{
+			name:     "multiple duplicate locations",
+			input:    "//folder//subfolder///file.txt",
+			expected: "/folder/subfolder/file.txt",
+		},
+		{
+			name:     "empty string",
+			input:    "",
+			expected: "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := removeDuplicateSlashes(tt.input)
+			if result != tt.expected {
+				t.Errorf("removeDuplicateSlashes(%q) = %q, want %q", tt.input, result, tt.expected)
+			}
+		})
+	}
+}
+