Couchbase cannot write documents to database

I am new to android and am trying to store an image in a database using couchbase mobile. When I try to run my code, logcat throws the error "Unable to write to the database. The current winning revision is not being removed, so this is a conflict." I don't know what I am doing wrong. Any help is appreciated. Here is my code.

        Document document = database.getDocument("test1");
        Map<String, Object> docContent = new HashMap<>();
        docContent.put("message", "Hello Couchbase Lite");
        docContent.put("creationDate", currentTimeString);
        docContent.put("Testing Message 1","Testing the sync of message");
        try {
            document.putProperties(docContent);
            UnsavedRevision newRev = document.createRevision();
            URL url = new URL("res/mipmap-mdpi-v4/sym_def_app_icon.png");
            newRev.setAttachment("photo.png", "image/png", url);
            newRev.save();
            Log.d (TAG, "Document written to database named " + dbname + " with ID = " + document.getId());
            } 
        catch (CouchbaseLiteException e) {
            Log.e(TAG, "Cannot write document to database", e);
            }
        catch (MalformedURLException e) {
            e.printStackTrace();
        }