The property 'Id' on entity type 'EntityMapping' has a temporary value

Problem uploading products via excel files .
They upload fine for several files and then the site crashes on upload attempt :

No webpage was found for the web address: http://mysite.com/Admin/Product/ImportExcel
HTTP ERROR 404

I check the product list and some products made it but the images did not upload . Not all products made it to the list .

I tried re-uploading excel with just one of the products and I used one of the products
that uploaded successfully with its image and I just changed the SKU . Still won't upload the image .
So has nothing to do with the image .

I see in the logs :

"The property 'Id' on entity type 'EntityMapping' has a temporary value while attempting to change the entity's state to 'Unchanged'. Either set a permanent value explicitly or ensure that the database is configured to generate values for this property."

I can't tell if this is related as this log is from the other day when I was making the upload attempts but I don't know what time it was . Now when I make an upload attempt , the logs are not updated . Seems the logs are not updated right away ?

In the database , Product_Picture_Mapping was not updated .

What version of nopCommerce?  SQL Server?

Nopcommerce 4.1
SQL Server 2016 express

It could be related to this (which may only be fixed in 4.10)
https://www.nopcommerce.com/boards/t/55329/v41-insert-entity-when-the-entity-has-unique-constraint.aspx

Or possibly it's a problem with SQL Express.  (Which is not used often, so may not have gone through much testing with nopCommerce.)

For the first item you mention , that should be fixed in 4.10 correct ?

As far as SQL Server issue , why are most products uploading though ?
If was SQL Server issue , none would upload ?

This is fixed by my hoster ... my site went down actually today and hoster says I had database disk space issues .
Now imports are working again .