diff --git a/weed/s3api/s3api_object_handlers.go b/weed/s3api/s3api_object_handlers.go
index 6c1a824b4..a53e2d7ef 100644
--- a/weed/s3api/s3api_object_handlers.go
+++ b/weed/s3api/s3api_object_handlers.go
@@ -1280,12 +1280,12 @@ func (s3a *S3ApiServer) setResponseHeaders(w http.ResponseWriter, entry *filer_p
 		for k, v := range entry.Extended {
 			// Skip internal SeaweedFS headers
 			if !strings.HasPrefix(k, "xattr-") && !s3_constants.IsSeaweedFSInternalHeader(k) {
-				// Support backward compatibility: migrate old lowercase format to canonical format
-				// OLD: "x-amz-meta-foo" → NEW: "X-Amz-Meta-foo"
+				// Support backward compatibility: migrate old non-canonical format to canonical format
+				// OLD: "x-amz-meta-foo" → NEW: "X-Amz-Meta-foo" (preserving suffix case)
 				headerKey := k
 				if strings.HasPrefix(strings.ToLower(k), "x-amz-meta-") && !strings.HasPrefix(k, s3_constants.AmzUserMetaPrefix) {
-					// Old format detected - normalize to canonical prefix
-					suffix := strings.ToLower(k[len("x-amz-meta-"):])
+					// Old format detected - normalize to canonical prefix, preserve suffix case
+					suffix := k[len("x-amz-meta-"):]
 					headerKey = s3_constants.AmzUserMetaPrefix + suffix
 					glog.V(4).Infof("Migrating old user metadata header %q to %q in response", k, headerKey)
 				}
diff --git a/weed/s3api/s3api_object_handlers_copy.go b/weed/s3api/s3api_object_handlers_copy.go
index ce65534b4..e52fbc71d 100644
--- a/weed/s3api/s3api_object_handlers_copy.go
+++ b/weed/s3api/s3api_object_handlers_copy.go
@@ -700,29 +700,22 @@ func processMetadataBytes(reqHeader http.Header, existing map[string][]byte, rep
 	if replaceMeta {
 		for header, values := range reqHeader {
 			if strings.HasPrefix(header, s3_constants.AmzUserMetaPrefix) {
-				// AWS S3 stores user metadata keys in lowercase
 				// Go's HTTP server canonicalizes headers (e.g., x-amz-meta-foo → X-Amz-Meta-Foo)
-				// Preserve the canonical prefix "X-Amz-Meta-" but lowercase the user-defined suffix
-				suffix := strings.ToLower(header[len(s3_constants.AmzUserMetaPrefix):])
-				normalizedKey := s3_constants.AmzUserMetaPrefix + suffix
+				// We store them as they come in (after canonicalization) to preserve the user's intent
 				for _, value := range values {
-					metadata[normalizedKey] = []byte(value)
+					metadata[header] = []byte(value)
 				}
 			}
 		}
 	} else {
-		// Copy existing metadata as-is (already normalized during storage)
-		// Support both old format (x-amz-meta-*) and new format (X-Amz-Meta-*) for backward compatibility
+		// Copy existing metadata as-is
 		for k, v := range existing {
 			if strings.HasPrefix(k, s3_constants.AmzUserMetaPrefix) {
-				// New format (X-Amz-Meta-foo) - copy as-is
 				metadata[k] = v
 			} else if strings.HasPrefix(strings.ToLower(k), "x-amz-meta-") {
-				// Old format (x-amz-meta-foo) - migrate to new format
-				suffix := strings.ToLower(k[len("x-amz-meta-"):])
-				normalizedKey := s3_constants.AmzUserMetaPrefix + suffix
-				metadata[normalizedKey] = v
-				glog.V(4).Infof("Migrating old user metadata key %q to %q", k, normalizedKey)
+				// Backward compatibility: old format (x-amz-meta-foo)
+				// Preserve the original key from storage for backward compatibility
+				metadata[k] = v
 			}
 		}
 	}
diff --git a/weed/s3api/s3api_object_handlers_put.go b/weed/s3api/s3api_object_handlers_put.go
index 6ef0dcf97..018eb2b1e 100644
--- a/weed/s3api/s3api_object_handlers_put.go
+++ b/weed/s3api/s3api_object_handlers_put.go
@@ -447,13 +447,9 @@ func (s3a *S3ApiServer) putToFiler(r *http.Request, uploadUrl string, dataReader
 	for k, v := range r.Header {
 		if len(v) > 0 && len(v[0]) > 0 {
 			if strings.HasPrefix(k, s3_constants.AmzUserMetaPrefix) {
-				// AWS S3 stores user metadata keys in lowercase
 				// Go's HTTP server canonicalizes headers (e.g., x-amz-meta-foo → X-Amz-Meta-Foo)
-				// Preserve the canonical prefix "X-Amz-Meta-" but lowercase the user-defined suffix
-				// This ensures the key is still detectable via prefix checks elsewhere
-				suffix := strings.ToLower(k[len(s3_constants.AmzUserMetaPrefix):])
-				normalizedKey := s3_constants.AmzUserMetaPrefix + suffix
-				entry.Extended[normalizedKey] = []byte(v[0])
+				// We store them as they come in (after canonicalization) to preserve the user's intent
+				entry.Extended[k] = []byte(v[0])
 			} else if k == "Cache-Control" || k == "Expires" || k == "Content-Disposition" {
 				entry.Extended[k] = []byte(v[0])
 			}
diff --git a/weed/server/filer_server_handlers_write_autochunk.go b/weed/server/filer_server_handlers_write_autochunk.go
index 59b83501b..f2449ab52 100644
--- a/weed/server/filer_server_handlers_write_autochunk.go
+++ b/weed/server/filer_server_handlers_write_autochunk.go
@@ -544,14 +544,10 @@ func SaveAmzMetaData(r *http.Request, existing map[string][]byte, isReplace bool
 
 	for header, values := range r.Header {
 		if strings.HasPrefix(header, s3_constants.AmzUserMetaPrefix) {
-			// AWS S3 stores user metadata keys in lowercase
 			// Go's HTTP server canonicalizes headers (e.g., x-amz-meta-foo → X-Amz-Meta-Foo)
-			// Preserve the canonical prefix "X-Amz-Meta-" but lowercase the user-defined suffix
-			// This ensures the key is still detectable via prefix checks elsewhere
-			suffix := strings.ToLower(header[len(s3_constants.AmzUserMetaPrefix):])
-			normalizedKey := s3_constants.AmzUserMetaPrefix + suffix
+			// We store them as they come in (after canonicalization) to preserve the user's intent
 			for _, value := range values {
-				metadata[normalizedKey] = []byte(value)
+				metadata[header] = []byte(value)
 			}
 		}
 	}