Parsing, add attitude. Unable to encode link to unsaved ParseObject

I am trying to add a relation to users of a table with bars in a table pane. Bars already exist in my database, but I always get the error "Unable to encode communication with unsaved ParseObject".

ParseUser user = ParseUser.getCurrentUser();
ParseObject barParseObject = ParseObject.createWithoutData(TABLE_BAR, bar.getBarId());
ParseRelation<ParseObject> relation = user.getRelation(ApiUserMapper.FIELD_LIKES);

if (bar.isFavourite()) {
    relation.add(barParseObject);
} else {
    relation.remove(barParseObject);
}
user.saveInBackground(new SaveCallback() {
    @Override
    public void done(ParseException e) {
        if (e == null) {
            resultCallback.processResults(bar);
        } else {
            if (BuildConfig.DEBUG) {
                Log.e(TAG, "Error: updateFav " + e.getMessage());
            } 
            resultCallback.processError(e);
        }
    }
});

      

        
        
        
      

    

bar.getBarId () contains a valid ObjectId already stored in the database, but I also tried requesting this bar earlier with the same result.

ParseQuery<ParseObject> query = ParseQuery.getQuery(TABLE_BAR);
query.getInBackground(bar.getBarId(), new GetCallback<ParseObject>() {
    public void done(ParseObject object, ParseException e) {
        if (e == null) {
            ParseRelation<ParseObject> relation = user.getRelation(ApiUserMapper.FIELD_LIKES);

            if (bar.isFavourite()) {
                relation.add(object);
            } else {
                relation.remove(object);
            }
            user.saveInBackground(new SaveCallback() {
                @Override
                public void done(ParseException e) {
                    if (e == null) {
                        resultCallback.processResults(bar);
                    } else {
                        if (BuildConfig.DEBUG) {
                            Log.e(TAG, "Error: updateFav " + e.getMessage());
                        }
                        resultCallback.processError(e);
                    }
                }
            });
        }
    }
});

      

        
        
        
      

    

If I try to add the relation the other way around, it works fine. But I want the relationship to be added to the User table.

ParseObject barParseObject = ParseObject.createWithoutData(TABLE_BAR, bar.getBarId());
        ParseRelation<ParseObject> relation = barParseObject.getRelation(ApiUserMapper.FIELD_LIKES);
        relation.add(user);
        barParseObject.saveInBackground(new SaveCallback() {
            @Override
            public void done(ParseException e) {
                if (e == null) {
                    resultCallback.processResults(bar);
                } else {
                    if (BuildConfig.DEBUG) {
                        Log.e(TAG, "Error: updateFav " + e.getMessage());
                    } else {
                        Crashlytics.log(LOG_PRIORITY, TAG, "Error: updateFav " + e.getMessage());
                    }
                    resultCallback.processError(e);
                }
            }
        });

      

        
        
        
      

    

Any hints? Something to do with permissions? I am assuming the current user can write their own data, but I do not have any specific setting in my code.

Thank!