I've developed a code to upload a file to dropbox since LWC. It doesn't work.

The File Upload LWC component returned a ContentDocumentId once the file is uploaded. 
The Dropbox API to upload a file requires the file location to send it to the Dropbox folder. I've tried to send in the body the file content, taken from ContentVersion.VersionData but it doesn't work. A file in Dropbox is created with unreadable content.
How could I solve it?
Here is my code 

@AuraEnabled
    public static String uploadFile(Id documentId, Id recordId, String path){

        path = createFolder(recordId);

        Metadata fileMetadata;

        ContentVersion file = [Select Id, Title, contentdocumentid, FileExtension, VersionData, PathOnClient from ContentVersion where islatest = true and contentdocumentid =: documentId LIMIT 1 ];

        GUIJE_OAuthController.OAuth oAuthInstance = GUIJE_OAuthController.getOAuthByName(PROVIDER_NAME);

        HttpRequest request = new HttpRequest();

        if(!String.isBlank(oAuthInstance.access_token)){

            request.setHeader('Authorization', String.format('Bearer {0}', new List<String>{oAuthInstance.access_token}));
        }
        else {
            //@todo reset token;
        }

        
        request.setMethod('POST');
        request.setTimeout(60000);
        request.setEndpoint('https://content.dropboxapi.com/2/files/upload');

        UploadFile upfile = new UploadFile(path+'/'+file.Title+'.'+file.FileExtension);


        request.setHeader('Dropbox-API-Arg', JSON.serialize(upfile));
        request.setHeader('Content-Type', 'application/octet-stream');
        

        String attachmentBody = EncodingUtil.base64Encode(file.VersionData);

        request.setBody(attachmentBody);



        request.setBody(EncodingUtil.base64Encode(file.VersionData));

        HttpResponse response = GUIJE_REST.send(request);

        if (response.getStatusCode() == 201 || response.getStatusCode() == 200) {
               

            fileMetadata = (Metadata) JSON.deserialize(response.getBody(), Metadata.class);

            
        }
        else {

            System.debug(response.getStatus());
            fileMetadata = new Metadata();
            fileMetadata.error = JSON.serialize(response.getStatus());
        }

        return JSON.serialize(fileMetadata);

    }

Thanks