if err != nil {
			writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
			return
		}
		if dstOpts.IndexCB != nil {
			dstOpts.IndexCB = compressionIndexEncrypter(objectEncryptionKey, dstOpts.IndexCB)
		}
	}

	srcInfo.PutObjReader = pReader
	copyObjectPart := objectAPI.CopyObjectPart

	// Copy source object to destination, if source and destination

	PrefixEnabledFn func(prefix string) bool // function which returns true if versioning is enabled on prefix

	// IndexCB will return any index created but the compression.
	// Object must have been read at this point.
	IndexCB func() []byte

	// InclFreeVersions indicates that free versions need to be included
	// when looking up a version by fi.VersionID
	InclFreeVersions bool

	partPath := pathJoin(uploadIDPath, fi.DataDir, partSuffix)

	md5hex := r.MD5CurrentHexString()
	if opts.PreserveETag != "" {
		md5hex = opts.PreserveETag
	}

	var index []byte
	if opts.IndexCB != nil {
		index = opts.IndexCB()
	}

	actualSize := data.ActualSize()
	if actualSize < 0 {
		_, encrypted := crypto.IsEncrypted(fi.Metadata)
		compressed := fi.IsCompressed()
		switch {
		case compressed:

			pi, err := z.PutObjectPart(ctx, bucket, objInfo.Name, res.UploadID,
				part.Number,
				NewPutObjReader(hr),
				ObjectOptions{
					PreserveETag: part.ETag, // Preserve original ETag to ensure same metadata.
					IndexCB: func() []byte {
						return part.Index // Preserve part Index to ensure decompression works.
					},
					NoAuditLog: true,
				})
			if err != nil {

			pi, err := z.PutObjectPart(ctx, bucket, oi.Name, res.UploadID,
				part.Number,
				NewPutObjReader(hr),
				ObjectOptions{
					PreserveETag: part.ETag, // Preserve original ETag to ensure same metadata.
					IndexCB: func() []byte {
						return part.Index // Preserve part Index to ensure decompression works.
					},
					NoAuditLog: true,
				})
			if err != nil {