When deleting a product tag on the product edit admin page and saving changes, the tag is not getting removed from the product.  Verified on local copy and GrandNode 4.40 demo site.

Thank you for bug report. Here is work item.

Hi,
Fixed 85f23ce

Regards
Krzysztof

Thanks for the quick turnaround.

Deleting a product tag for a product is throwing a null reference exception if a tag contains uppercase letters.

System.NullReferenceException: Object reference not set to an instance of an object.
at Grand.Web.Areas.Admin.Services.ProductViewModelService.SaveProductTags(Product product, String[] productTags) in C:\dev\Grand.Web\Areas\Admin\Services\ProductViewModelService.cs:line 192

Also, adds lowercase tags to product record, essentially duplicating tags.

Hi Rich,
Is your database comes from version 4.30 or 4.40 ?

Regards
Krzysztof

We started with a new 4.40 database.  We wrote a custom product import process to load our products, product tags, and categories.  We use the following code to create new product tags:

                var productTag = _productTagService.GetProductTagByName(tagName);
                if (productTag == null)
                {
                    //add new product tag
                    productTag = new ProductTag
                    {
                        Name = tagName,
                        Count = 0,
                    };
                    _productTagService.InsertProductTag(productTag);
                }

Looks like we have to force our tags to lowercase before inserting.  Should the lowercase constraint be enforced at the service level inside of _productTagService.InsertProductTag(productTag)?

Yes, you need change to lowercase. When user adding tags in admin panel - it always change name to lowercase.
We will add change to lowercase in service. Thanks for suggestions.
In the application there are more such changes about lowercase.
For example: Email in Customer, Coupon Code, Gift Card.
This is due to better performance MongoDB, but for end user it doesn't matter.

Best Regards
Krzysztof