diff --git a/rustfs/src/storage/ecfs.rs b/rustfs/src/storage/ecfs.rs
index a1981d07..9f584d60 100644
--- a/rustfs/src/storage/ecfs.rs
+++ b/rustfs/src/storage/ecfs.rs
@@ -117,10 +117,9 @@ use rustfs_utils::{
         AMZ_BUCKET_REPLICATION_STATUS, AMZ_CHECKSUM_MODE, AMZ_CHECKSUM_TYPE,
         headers::{
             AMZ_DECODED_CONTENT_LENGTH, AMZ_OBJECT_TAGGING, AMZ_RESTORE_EXPIRY_DAYS, AMZ_RESTORE_REQUEST_DATE,
-            RESERVED_METADATA_PREFIX_LOWER,
+            RESERVED_METADATA_PREFIX, RESERVED_METADATA_PREFIX_LOWER,
         },
     },
-    obj::extract_user_defined_metadata,
     path::{is_dir_object, path_join_buf},
 };
 use rustfs_zip::CompressionFormat;
@@ -1075,6 +1074,7 @@ impl S3 for FS {
             metadata,
             copy_source_if_match,
             copy_source_if_none_match,
+            content_type,
             ..
         } = req.input.clone();
         let (src_bucket, src_key, version_id) = match copy_source {
@@ -1090,6 +1090,19 @@ impl S3 for FS {
         validate_object_key(&src_key, "COPY (source)")?;
         validate_object_key(&key, "COPY (dest)")?;
 
+        // AWS S3 allows self-copy when metadata directive is REPLACE (used to update metadata in-place).
+        // Reject only when the directive is not REPLACE.
+        if metadata_directive.as_ref().map(|d| d.as_str()) != Some(MetadataDirective::REPLACE)
+            && src_bucket == bucket
+            && src_key == key
+        {
+            error!("Rejected self-copy operation: bucket={}, key={}", bucket, key);
+            return Err(s3_error!(
+                InvalidRequest,
+                "Cannot copy an object to itself. Source and destination must be different."
+            ));
+        }
+
         // warn!("copy_object {}/{}, to {}/{}", &src_bucket, &src_key, &bucket, &key);
 
         let mut src_opts = copy_src_opts(&src_bucket, &src_key, &req.headers).map_err(ApiError::from)?;
@@ -1214,12 +1227,35 @@ impl S3 for FS {
             src_info
                 .user_defined
                 .remove(&format!("{RESERVED_METADATA_PREFIX_LOWER}compression"));
+            src_info
+                .user_defined
+                .remove(&format!("{RESERVED_METADATA_PREFIX}compression"));
             src_info
                 .user_defined
                 .remove(&format!("{RESERVED_METADATA_PREFIX_LOWER}actual-size"));
+            src_info
+                .user_defined
+                .remove(&format!("{RESERVED_METADATA_PREFIX}actual-size"));
             src_info
                 .user_defined
                 .remove(&format!("{RESERVED_METADATA_PREFIX_LOWER}compression-size"));
+            src_info
+                .user_defined
+                .remove(&format!("{RESERVED_METADATA_PREFIX}compression-size"));
+        }
+
+        // Handle MetadataDirective REPLACE: replace user metadata while preserving system metadata.
+        // System metadata (compression, encryption) is added after this block to ensure
+        // it's not cleared by the REPLACE operation.
+        if metadata_directive.as_ref().map(|d| d.as_str()) == Some(MetadataDirective::REPLACE) {
+            src_info.user_defined.clear();
+            if let Some(metadata) = metadata {
+                src_info.user_defined.extend(metadata);
+            }
+            if let Some(ct) = content_type {
+                src_info.content_type = Some(ct.clone());
+                src_info.user_defined.insert("content-type".to_string(), ct);
+            }
         }
 
         let mut reader = HashReader::new(reader, length, actual_size, None, None, false).map_err(ApiError::from)?;
@@ -1304,16 +1340,6 @@ impl S3 for FS {
                 .insert("x-amz-server-side-encryption-customer-key-md5".to_string(), sse_md5.clone());
         }
 
-        if metadata_directive.as_ref().map(|d| d.as_str()) == Some(MetadataDirective::REPLACE) {
-            let src_user_defined = extract_user_defined_metadata(&src_info.user_defined);
-            src_user_defined.keys().for_each(|k| {
-                src_info.user_defined.remove(k);
-            });
-            if let Some(metadata) = metadata {
-                src_info.user_defined.extend(metadata);
-            }
-        }
-
         // check quota for copy operation
         if let Some(metadata_sys) = rustfs_ecstore::bucket::metadata_sys::GLOBAL_BucketMetadataSys.get() {
             let quota_checker = QuotaChecker::new(metadata_sys.clone());