The default value of one of the characteristics of that product isn't available

Hi,

That means that you have some discrepency in the data of the variants of the product.
If you edit the product in the backend, you can access the list of variants under its "variants" tab.
There, you'll find a listing of the variants with a "default" column. In that column, you can see which variant is the default one. Normally, each product has one default variant.
That message indicates that the variant which is selected as default uses a value of a characteristic which has been removed from the characteristic when you edit it in the menu Products>Charactersitics.
So you need to check the variants of that product, and maybe select a new default variant or resave the default variant.

Hi,

There should be several ways. But I don't know what you did to reach that situation and I don't know how your product and its characteristics and variants are currently configured so it's hard to say anything precise.
The simplest and cleanest is this:
- delete all the variants of the product
- add back all the variants and reconfigure them

The quick and dirty solution is to remove the line

$app->enqueueMessage('The default value of one of the characteristics of that product isn\'t available as a variant. Please check the characteristics and variants of that product');